Monsoon Rain 2026: The Meteorological Department has warned of rain and thunderstorms in Mumbai, Pune, Thane, Raigad, Ratnagiri, and Palghar districts. Moderate to heavy rain is also expected in Mumbai, while pre-monsoon rains in Pune have brought relief from the heat. Meanwhile, temperatures in northern Maharashtra and Marathwada are above 40 degrees Celsius.
The weather in Maharashtra is changing these days. The India Meteorological Department (IMD) has issued a warning of rain and thunderstorms in districts like Mumbai, Pune, Thane, Raigad, Ratnagiri, and Palghar. Regarding the weather in Mumbai, the sky has been overcast since this morning, with light rain rain occurring at some locations. According to the weather department’s forecast, moderate to heavy rain is expected throughout the day in Mumbai. The maximum temperature is expected to be around 30-32 degrees Celsius. Weather refers to the air and atmospheric conditions of a place. It includes things like temperature, rainfall, wind speed, and humidity.
Most weather events on Earth occur in the lowest layer of the atmosphere, called the troposphere.
Weather varies because air pressure, temperature, and humidity vary from place to place, depending on the angle of sunlight and the latitude of the place.
In simple terms, weather tells us what the sky will be like today, tomorrow or on a particular day – hot, cold, rainy or sunny. Pune previously spelled in English as Poona is a city in the state of Maharashtra in the Deccan Plateau in Western India. Pune is known as the cultural capital of Maharashtra, and the Ganesh Festival celebrated here is famous throughout the country. Pune sees pre-monsoon showers; yet above-40 temperatures at several places across Maharashtra Pune received pre-monsoon showers on Friday, bringing relief from the heat, while other parts of Maharashtra experienced temperatures above 40 degrees Celsius.
It is a fictional representation created for illustrative purposes only.
Key Takeaways
- Pune received pre-monsoon showers on Friday even as large parts of Maharashtra witnessed temperatures above 40 degrees Celsius, the India Meteorological Department (IMD) said.
- Pune recorded 13.1-mm rainfall, bringing much-needed respite from the scorching heat, as the mercury logged 37 degrees Celsius.
- Satara too witnessed drizzles.
- Nandurbar in north Maharashtra recorded 40 degrees Celsius, while Malegaon clocked 41 degrees.
une received pre-monsoon showers on Friday even as large parts of Maharashtra witnessed temperatures above 40 degrees Celsius, the India Meteorological Department (IMD) said.
Pune recorded 13.1-mm rainfall, bringing much-needed respite from the scorching heat, as the mercury logged 37 degrees Celsius. Satara too witnessed drizzles.
Nandurbar in north Maharashtra recorded 40 degrees Celsius, while Malegaon clocked 41 degrees.
Parbhani and Chhatrapati Sambhajinagar in Marathwada saw maximum temperature at 41.3 and 41.4 degrees Celsius, respectively. The Colaba observatory, the base station for Mumbai recorded 35 degrees Celsius, while Santacruz logged 34.5 degrees Celsius for the suburbs, the IMD said.
Rainfall Highlights in Pune
- Shivajinagar & Pashan: Logged 13.1 mm of light-to-moderate rainfall.
- Chinchwad: Faced the heaviest downpour with 60 mm of localized precipitation.
- Hadapsar: Recorded 37.5 mm of rain.
- NDA: Registered 29.5 mm of showers.
- General Conditions: Sudden dark skies, lightning, gusty winds of 30–40 kmph, and isolated hail lowered temperatures down to 37°C.
Thunderstorm breaks Pune’s heat spell as dark skies, lightning and rain sweep across city thundershowers expected next week in Pune weather office has forecast relief for Pune this week. In the last few days, the maximum temperatures have been closer to 40 degrees Celsius but, the coming week will experience a gradual fall in temperatures, especially the maximum temperature, as the Westerly winds strengthen, bringing moisture into the region. “We will begin to see the slightly cooling temperatures from May 19 itself,” said Dr Sudeep Kumar, scientist at the India Meteorological Department, Pune.
On May 11, Pune’s main weather station at Shivajinagar had recorded a maximum temperature of 41.4 degrees Celsius, which was the highest on a May day since 2015. Two days later, Pune’s morning temperature was setting a record, when the minimum at Shivajinagar touched 27.4 degrees Celsius, making it one of the four hottest days of May since 1969. According to a weather expert, the first half of May in Pune this year was warmer than it has ever been during the same period since 2020.
On Monday, however, Shivajinagar recorded a minimum temperature of 24 degrees Celsius, which was a drop from 25.5 degrees Celsius the day before. In Lohegaon, which had touched a minimum temperature of 29.2 degrees Celsius, 6.9 degrees Celsius above normal, last week, the morning was cooler, at 26 degrees Celsius on monday. This was still 2.6 degrees Celsius above normal. Hadapsar had one of the warmest mornings of Pune, with the mercury touching 28 degrees Celsius, followed by Koregaon Park, at 27.2 degrees Celsius, and Magarpatta and Wadgaonsheri, at around 26.7 degrees Celsius. In Pashan, it was more pleasant, at 22.5 degrees Celsius, while Lavale would have felt quote cool in the morning, with a minimum temperature of 22.2 degrees Celsius.
The maximum temperature was 40 degrees Celsius in Shivajinagar on May 18, which was 3.1 degrees above normal, and 41.8 degrees Celsius in Lohegaon, almost 5 degrees Celsius above normal. Pashan, which is generally among the cooler parts of Pune, was one of the warmest parts of Pune, at 40.3 degrees Celsius, almost the same as Hadapsar and Wadgaonsheri, where the daytime temperature was 38.5 and 39.4 degrees Celsius, respectively. According to the IMD, the minimum temperature is likely to be around 24 degrees Celsius in Shivajinagar, 23 degrees Celsius and Chinchwad in Pashan, and around 26 degrees Celsius in Lohegaon, Magarpatta and Koregaon Park for the next two days. By May 24, it would have dropped to 22 degrees Celsius in Pune, Pashan, Chinchwad, NDA and Lavale. In Koregaon Park, Magarpatta and Lohegaon, the minimum temperature is likely to be around 24 degrees Celsius. The maximum temperature is forecast to be between 36 and 38 degree C by May 24 in most parts of the city.
“IMD has forecast thunderstorms, lightning and squalls over parts of Madhya Maharashtra, Marathwada and Vidarbha. In Pune, we are expecting clouds in the afternoon and evening. Between May 22 and 24, there is also a chance of thunderstorms in Pune,” said Dr Sudeep. By 6 pm, Shivajinagar and Pashan had received 13.1 mm of rain. Chinchwad recorded the highest rainfall at 60 mm, followed by Hadapsar with 37.5 mm, NDA 29.5 mm, Koregaon Park 9.5 mm and Lavale 4.5 mm.
In meteorological parlance, this was classified as “light to moderate” rain, but the city was not complaining. The sudden cool breeze and the warm smell of wet earth came as a welcome relief after days of intense heat, even if temperatures were slightly lower than those recorded last week.
“We had noticed significant heating, with the maximum temperature in Shivajinagar rising to 37°C. At the same time, there was moisture incursion from the Arabian Sea. Since daytime temperatures played a role in triggering the rainfall, the weather office pointed out that Magarpatta, the warmest part of the city on Friday, recorded a maximum temperature of 41.5°C. In Pashan, the maximum temperature dropped marginally from 38.5°C on Thursday to 37.6°C on Friday.
In Lohegaon, which has reeled under heatwave-like conditions for much of this month, the daytime temperature on Friday stood at 39.2°C, or 2.6 degrees above normal. However, it offered slight relief compared to the 40°C recorded 24 hours earlier. Chinchwad ended the week with a maximum temperature of 35.4°C, cooler than Koregaon Park, which recorded 37.3°C during the day.
The IMD has issued a yellow alert — indicating that people should remain informed but that conditions are not severe — for parts of Central Maharashtra and Marathwada on May 23, warning of thunderstorms, lightning and squalls. Sanap added that the rain was unrelated to the monsoon. While the monsoon has set in over the Andaman and Nicobar Islands, it has yet to reach Kerala, after which it will gradually advance northwards towards Maharashtra.
For Pune, the IMD has forecast a maximum temperature of 40°C in Shivajinagar and Pashan over the next two days. Lohegaon, Koregaon Park and Magarpatta are expected to witness maximum temperatures of 42°C on May 23 and 24. The city’s minimum temperature is expected to remain between 23°C and 27°C.
Meanwhile, a red alert for severe heatwave conditions and warm nights has been issued for Vidarbha and is expected to remain in force till May 24. On Friday, Bramhapuri in Vidarbha recorded the highest maximum temperature in Maharashtra at 47°C, which was 4.6 degrees above normal. Temperature Breakthroughs Across Maharashtra Pune and Satara observed drizzles and temperature dips, severe heat continues to impact other regions: Cooler days as temps dip; gradual rise expected now
Pune: After days of rainy weather, a noticeable dip in both day and night temperatures is being seen across Maharashtra, bringing brief relief from the early April heat.In Pune, Shivajinagar recorded a minimum temperature of 18.1°C, while NDA was cooler at 17.3°C. Daytime temperatures also remained subdued, with maximums hovering around 33-34°C across city stations — a clear drop compared to recent hotter days.
Lohegaon recorded a slightly higher maximum of around 36.6°C.Across the state, the cooling trend was visible. Mahabaleshwar recorded the lowest minimum temperature at 17.2°C, while Solapur remained among the hottest at 38.2°C. Many stations in Madhya Maharashtra saw maximum temperatures below normal by 1-4 degrees, while in Nashik, the day temp was 32.4°C, a significant 8 degrees below normal. IMD’s local forecast for Pune indicated mainly clear to partly clear skies, with maximum and minimum temperatures expected to be around 36°C and 18°C, respectively, on Sunday. India Meteorological Department (IMD) is an agency under Ministry of Earth Sciences of the Government of India which is responsible for meteorological observations, weather forecasting and seismology. It has the responsibility for forecasting, naming and distribution of warnings for tropical cyclones in the Northern Indian Ocean region, including the Malacca Straits, the Bay of Bengal, the Arabian Sea and the Persian Gulf. Minimum temperatures are expected to fall slightly by 1-3 degrees till Sunday, before rising again by a similar margin.
Brahmapuri (Vidarbha)47.2°C (Extremely Severe Heatwave)
DISTRICT AT A GLANCE · Area : 10,138 Square Kilometers · Census : 37,01,282 · Literacy rate : 79.02% · Taluka : 10 · Mandal : 84 · Talathi Sajja : 490. Aurangabad (), officially renamed as Chhatrapati Sambhajinagar in 2023, is a city in the Indian state of Maharashtra. Welcome to Chhatrapati Sambhajinagar (also spelled as Chhatrapati Sambhaji Nagar), a historic city in Maharashtra, offering a confluence of culture. Residents of Parbhani city are referred to as Parbhanikar. In ancient times, Parbhani city was known as Prabhavatinagari. Parbhani city was named Prabhavatinagari due to the presence of an ancient temple of Goddess Prabhavati. Malegaon is a city in Nashik District of Maharashtra State in India. It is situated on the bank of the Girna river with Mosam River river flowing.
Malegaon is a Town in Malegaon Taluka in Washim District of Maharashtra State, India. It belongs to Vidarbha region. It belongs to Amravati Division.
Mumbai (Colaba / Santacruz)34.5°C to 35°C (Humid but stable)
Southwest Monsoon Trajectory
Andaman & Nicobar Islands: Already covered by the advancing front.
Kerala Onset: Predicted to make landfall by May 26, 2026 (nearly a week earlier than normal).
Maharashtra & North India: Anticipated to advance steadily northward through June if current speed persists. The 2026 Indian Southwest Monsoon onset is expected in the next two weeks
The Indian Southwest Monsoon will reach India in the next two weeks, but a developing El Niño could signal a drier than normal monsoon for businesses and major industries across the country.
Southwest monsoon onset over southern India in the next two weeks
The Indian Meteorological Department (IMD) is responsible for tracking the advance and retreat of the monsoon over India. This weekend, the IMD issued the first progression of the northern limits of the southwest monsoon, just reaching the Andaman Sea and Andaman & Nicobar Islands on 16 May 2026, over the southern reaches of the Bay of Bengal.
INDIA METEOROLOGICAL DEPARTMENT
Forecast of the Onset Date of Southwest Monsoon – 2026 over Kerala
- Background
The advance of the southwest monsoon over the Indian mainland is marked by monsoon
onset over Kerala and is an important indicator characterizing the transition from the hot and dry
season to the rainy season. As the monsoon progresses northward, relief from scorching summer temperatures is experienced over the areas. Southwest monsoon normally sets in over Kerala on 1st June with a standard deviation of about 7 days. India Meteorological Department (IMD) has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 onwards. An indigenously developed state-of-the-art statistical model with a model error of ± 4 days is used for the purpose. The 6 Predictors used in the models are; i) Minimum Temperatures over North-west India, ii) Pre-monsoon rainfall peak over south Peninsula, iii) Outgoing Long wave Radiation (OLR) over south China Sea, (iv) Lower tropospheric zonal wind over southeast Indian ocean, (v) Outgoing Long wave Radiation (OLR) over the south-west Pacific region, and (vi) Lower tropospheric zonal wind over Northeast Indian Ocean.
IMD’s operational forecasts of the date of monsoon onset over Kerala during the past 21
years (2005-2025) were proved to be correct except in 2015. Forecast verification for the recent 6
years (2020-2025) is given in the table below. - Forecast for the 2026 Monsoon Onset over Kerala
This year, the southwest monsoon is likely to set in over Kerala on 26th May with a
model error of ± 4 days.
Year Actual Onset Date Forecast Onset Date
2020 1
st June 5
th June
2021 3
rd June 31st May
2022 29th May 27th May
2023 8
th June 4
th June
2024 30th May 31st May
2025 24th May 27th May
Image: Advance of the 2026 southwest monsoon onset (blue) and the normal dates of onset (red). Source: IMD
To make this early forecast onset date the IMD monitors these key monsoon predictors:
- Minimum temperatures over Northwest India;
- Pre-monsoon rainfall peak over South Peninsula;
- Cloudiness over the South China Sea and northeast Indian Ocean; and
- Trade wind strength over the southeast and northeast Indian Ocean.
The southwest monsoon is characterised by a surge of westerly winds extending 5-7 kilometres above sea level. These winds are laden with moisture from the Arabian Sea, bringing periods of heavy rainfall and squally conditions across much of southern India.
Image: Moisture laden monsoon clouds can be seen on satellite imagery moving from west to east over the southern Bay of Bengal on Saturday, 16 May 2026. Source: DTN
The southwest monsoon usually takes 4-6 weeks to progress into the far north of the country. The Western Ghats, an insurmountable mountain range along the west of India, splits the monsoon into the Arabian Sea and Bay of Bengal branches. The southwest monsoon usually takes 4-6 weeks to progress into the far north of the country. The Western Ghats, an insurmountable mountain range along the west of India, splits the monsoon into the Arabian Sea and Bay of Bengal branches.
INDIA METEOROLOGICAL DEPARTMENT
Long Range Forecast
For the 2026Southwest Monsoon Season Rainfall
Highlights
a) The 2026 southwest monsoon seasonal (June to September) rainfall over the
country as a whole is most likely to be below normal (95-90% of the Long
Period Average (LPA)). Quantitatively, the seasonal rainfall over the country as
a whole is likely to be 92% of LPA with a model error of ± 5%. The LPA of the
seasonal rainfall over the country as a whole based on the period of 1971-2020
is 87 cm.
b) At present, Weak La Niña–like conditions are transitioning to ENSO-neutral
conditions over the equatorial Pacific. Atmospheric circulation features across
the tropical Pacific remain consistent with weak La Niña–like conditions. The
Monsoon Mission Climate Forecast System (MMCFS) suggests the
development of El Niño conditions during the SW Monsoon season.
c) At present, neutral Indian Ocean Dipole (IOD) conditions are present over the
Indian Ocean and the latest Climate models forecast indicates that the positive
IOD conditions are likely to develop towards the end of the southwest monsoon
season.
d) The northern hemisphere snow cover extent during the last three months
(January to March 2026) was slightly below normal. Winter and spring snow
cover extent over Northern Hemisphere as well as Eurasia has a general inverse
relationship with the subsequent southwest monsoon seasonal rainfall over the
country.
e) IMD will issue the updated forecasts for monsoon season rainfall in the last week 2
Background
Since 2003, India Meteorological Department (IMD) has been issuing the
operational long-range forecast (LRF) for the southwest monsoon seasonal (June-
September) rainfall averaged over the country as a whole in two stages. The first stage
forecast is issued in April and the second stage or update forecast is issued bythe end
of May. In 2021, IMD has implemented a new strategy for issuing monthly and seasonal
operational forecasts for the southwest monsoon rainfall over the country by modifying
the existing two stage forecasting strategy. The new strategy uses both dynamical and
statistical forecasting system. Multi-Model Ensemble (MME) forecasting system based
on coupled global climate models (CGCMs) from different global climate prediction
centres, including IMD’s Monsoon Mission Climate Forecast System (MMCFS) are used
in dynamical forecast system.
As per the new LRF strategy, the first stage forecast issued in middle of April
consists of quantitative and probabilistic forecasts for the country as a whole, and the
spatial distribution of probabilistic forecasts for the tercile categories (above normal,
normal, and below normal) of the seasonal (June-September) rainfall over the country.
In the second stage forecast issued around end of May consist of update for the
seasonal rainfall forecast issued in April along with the probabilistic forecasts for the
seasonal rainfall over the four homogenous regions of India (northwest India, central
India, south Peninsula and northeast India) and monsoon core zone (MCZ). In addition,
quantitative and probabilistic forecasts for the country as a whole, and the spatial
distribution of probabilistic forecasts for the tercile categories (above normal, normal,
and below normal) of the June rainfall over the country are also issued during the
second stage forecast.
In continuation to the above forecasts, monthly rainfall forecast is issued around
end of June, July and August respectively for the subsequent one month. In addition,
quantitative and probabilistic forecasts for the country as a whole, and the spatial
distribution of probabilistic forecasts for the tercile categories for the second half of the
season rainfall is issued around end of July along with the forecast for August.
.
- Forecast for the 2026 Southwest monsoon Season (June–September)
rainfall over the country as a whole. The forecast based on both dynamical and statistical models suggests that quantitatively, the monsoon seasonal rainfall is likely to be 92% of the Long Period 3 Average (LPA) with a model error of ± 5%. The LPA of the seasonal rainfall over
the country as a whole for the period 1971-2020 is 87 cm.
The five-category probability forecast for the Seasonal (June to September)
rainfall over the country as a whole is given below. The forecast indicates that the
probabilities for both below normal and deficient rainfall categories are higher than their
respective climatological probabilities. The forecast probabilities for the “Above Normal”
and “Excess” rainfall categories are lower than their respective climatological
probabilities. Overall, the Southwest Monsoon seasonal rainfall over the country is most
likely to be below normal (90–95% of LPA).
The MME forecast for the 2026 southwest monsoon seasonal rainfall was
prepared based on the April initial conditions and using a group of coupled climate
models that having highest prediction skill over the Indian monsoon region.
The spatial distribution of probabilistic forecasts for tercile categories (above
normal, normal and below normal) for the seasonal rainfall (June to September) is
shown in Fig.1. The spatial distribution suggests that the below-normal seasonal rainfall
is most likely over many parts of the country except some areas over Northeast,
Northwest and South Peninsular India, where normal to above-normal rainfall is likely.
The white-shaded areas within the land area represent no signal from the model. - Sea Surface Temperature (SST) Conditions in the equatorial Pacific &
Indian Oceans
At present, Weak La Niña–like conditions are transitioning to ENSO-neutral
conditions over the equatorial Pacific. However, some atmospheric circulation features
across the tropical Pacific remain consistent with weak La Niña–like conditions. The
Category
Rainfall Range
(% of LPA)
Forecast
Probability (%)
Climatological
Probability (%)
Deficient < 90 35 16 Below Normal 90 – 95 31 17 Normal 96 -104 27 33 Above Normal 105-110 6 16 Excess > 110 1 17 4
latest forecasts from the Monsoon Mission Climate Forecast System (MMCFS)
suggest that ENSO-neutral conditions are most likely to continue during the April to
June 2026 season. The Monsoon Mission Climate Forecast System (MMCFS)
suggests the development of El Niño conditions during the SW Monsoon season.
Currently, neutral Indian Ocean Dipole (IOD) conditions are present over the
Indian Ocean and the latest Climate models forecast indicates that the positive IOD
conditions are likely to develop towards the end of the southwest monsoon season. .
As sea surface temperature (SST) conditions over the Pacific and the Indian
Oceans are known to have a strong influence on the Indian monsoon, IMD is carefully
monitoring the evolution of sea surface conditions over these Ocean basins. - Snow Cover over the Northern Hemisphere
The northern hemisphere snow cover extent during the last three months
(January to March 2026) was slightly below normal. Winter and spring snow cover
extent over Northern Hemisphere as well as Eurasia has a general inverse relationship
with the subsequent southwest monsoon seasonal rainfall over the country. 5
Fig.1.Probability forecast of tercile categories*
(below normal, normal, and above
normal) ofthe seasonal rainfall over India during the 2026 southwest monsoon
season (June -September). The figure illustrates the most likely categories as well
as their probabilities. The white shaded areas represent no signal from the
model.(Tercile categories have equal climatological probabilities, of 33.33% each).
What does a ‘super El Niño’ mean for Australia’s businesses?
There are signs that a very strong, or ‘super’ El Niño could develop in the tropical Pacific Ocean later this year. So, what does this mean for Australia’s weather during the second half of 2026?
El Niño on the horizon
The tropical Pacific Ocean is currently in a neutral state, meaning neither El Niño nor La Niña are occurring. However, there are strong indications that El Niño will emerge as we head into the Southern Hemisphere’s winter.
The first indicator of the looming El Niño is a large pool of abnormally warm water sitting beneath the surface of the tropical Pacific Ocean.
El Niño occurs when sea surface temperatures in the central equatorial Pacific Ocean – an area called the Niño 3.4 region – become warmer than average. The Bureau of Meteorology’s threshold for El Niño is at or above 0.8°C warmer than average in the Niño 3.4 region, while some other countries, including the United States, use a lower threshold of 0.5°C above average.
While ocean surface temperatures in the Niño 3.4 region are currently near average for this time of year, there is a large slab of unusually warm water sitting around 50 to 250 metres below the surface. These above-average sub-surface temperatures have strengthened in the last couple of months, with anomalies exceeding 6°C in some areas. It’s possible that these warm sub-surface waters will upwell towards the surface in the coming weeks and months, which could kick off El Niño.
Image: Sub-surface temperature anomalies in the equatorial Pacific Ocean from early March to early April, 2026. The red shading inside the green box shows abnormally warm water lying beneath the surface of the tropical Pacific Ocean. Source: Bureau of Meteorology.
A second sign that El Niño is about to emerge is overwhelming agreement between global forecast models.
At this time of year, we typically see a lot of uncertainty in forecasts for El Niño and La Niña due to a phenomenon called the autumn predictability barrier in the Southern Hemisphere (spring predictability barrier in the Northern Hemisphere). However, there is strong model consensus that El Niño will develop in the next few months.
Some models also predict that the imminent El Niño will become a very strong event – what is sometimes referred to as a ‘super El Niño’ – meaning sea surface temperatures in the Niño 3.4 region will reach 2.0°C above average or higher. According to the National Oceanic and Atmospheric Administration Climate Prediction Centre’s latest forecast, there is roughly a 25% chance of a very strong El Niño occurring towards the end of this year.
Image: El Niño forecast plume from the ECMWF SEAS5 model. Each red line represents a forecast from one of 51 different ensemble members from the same model. Each member uses slightly different initial ocean conditions as the basis for its forecast, which helps account for a range of possible scenarios in the forecast. Note that all ensemble members from this model are predicting El Niño conditions from May and most are suggesting a very strong, or ‘super’ El Niño later in the year. Source: ECMWF (annotated by Weatherzone).
What does El Niño mean for Australia?
El Niño does not guarantee any kind of weather for Australia. However, it does make some types of weather more likely than others, particularly during winter and spring.
The maps below show the observed changes to rainfall and maximum temperature from past El Niño events. These maps show conditions averaged out across multiple 9 or 10 El Niño years, representing the general impact of El Niño on daytime temperatures and rainfall.
Image: Observed rainfall deciles for the July to September period during 10 El Niño events from 1905 to 2015. The red shading shows where rainfall is below average. Source: Bureau of Meteorology.
Image: Observed maximum deciles for the August to October period during nine El Niño events from 1914 to 2015. The orange and yellow shading shows where maximum temperatures are above average while blue is below average. Source: Bureau of Meteorology.
In general, El Niño typically causes:
- Below average rainfall over large areas of Australia during winter and spring. However, its influence on rainfall is usually weaker in summer and autumn.
- Above average maximum temperatures for most areas outside the tropics, particularly during the second half of the year. In the tropics, El Niño typically reduces maximum temperatures in the dry season and makes days warmer in the wet season.
- Enhanced evaporation due to above average temperatures and below average rain, which can cause of enhance drought.
- More intense daily heat extremes in southern Australia, but with a reduced frequency of prolonged heatwaves.
- Increased frost risk in winter and spring due to enhanced radiative cooling with clearer skies.
- Increased risk of dangerous fire days in southeastern Australia as temperatures rise in spring and summer.
- Decreased seasonal peak alpine snow depths and a shorter snow season.
The strength of El Niño can also affect how it influences Australia’s weather. Stronger El Niño events make it more likely that the impacts mentioned above will occur. However, it is important to point out that stronger events do not always mean bigger weather impacts and even a weak El Niño can cause significant weather and climate impacts in Australia. It’s also worth noting that no two El Niño events are the same and other external influences, such as regional ocean temperatures near Australia, and other climate drivers, such as the Indian Ocean Dipole (IOD), will likely affect how El Niño impacts Australia in the coming months. We offer tailored solutions to protect assets, ensure worker safety, and optimise operations for industries like energy, mining, and transport, reducing financial losses from severe weather. The Walker Circulation: ENSO’s atmospheric buddy Reading back over the many excellent (if I do say so myself) posts here at the ENSO blog, there have been several re-occurring themes—the biggest of which is that ENSO is not just an ocean phenomena but an ocean-atmospheric interaction. ENSO is no one-man act. If the ocean is Abbott, then the atmosphere is Costello; the ocean…Laverne, the atmosphere…Shirley; the ocean…Kanye, the atmosphere…Kim. And just like there would be no “Kimye” without Kanye West and Kim Kardashian, there is no ENSO event without both an atmospheric and oceanic response. In June, the Bureau of Meteorology in Australia made an interesting observation that might shed light on the lack of coupling between the ocean and atmosphere (1). They pointed out that an anomalous sea surface temperature (SST) gradient was not in place across the equatorial Pacific Ocean. Like the gradient of a hill on a highway, an SST gradient describes a change in temperature across the ocean surface from one location to another (2).
The maps below show the typical evolution of SST anomalies leading up to wintertime El Niño events (winter is when ENSO is strongest). In this post, the SST gradient will refer to the difference in SST anomalies. “Anomalies” are the departures from the average state of the atmosphere or ocean. Blue shading shows where SSTs are below average, and red shading shows where SSTs are above average. In this case, the gradient refers to the more negative (cooler) SST anomalies in the western Pacific (blue shading) and the more positive (warmer) SST anomalies in the eastern Pacific (red shading).
So who cares whether “SST gradients” in the equatorial Pacific are in place? Well, as it turns out, the atmospheric circulation often responds to these SST gradients, and if they do not exist then it is possible that the growth of El Niño will be less energetic or reduced—like a car that will coast downhill (big gradient) on its own but not across a flat stretch of road (no gradient).
A stronger SST gradient produces stronger winds (3) blowing across the equatorial Pacific. A weaker gradient results in weaker winds. This concept can also work in reverse: stronger winds can lead to stronger SST gradients and weaker winds contribute to weaker SST gradients (4).
Normally, the SST gradient associated with ENSO becomes stronger as the winter approaches. The figure above shows the growth of the ENSO-related gradient between the western and eastern SST anomalies for the months of April through December. In April, May, and June, the gradient is typically not very strong, though there is still a difference between the warmer SSTs in the eastern Pacific and the near average SSTs in the western Pacific (near average SSTs shown by the light colors or white regions).
This year however, the SST gradient is weak- to- nonexistent, as shown by above-average SSTs in both the western and eastern equatorial Pacific Ocean.
Because of these coupled feedbacks (e.g. winds can both cause and be caused by the SST gradient), it is difficult for ENSO forecasters to determine whether the ocean is pushing the atmosphere or the atmosphere is pushing the ocean. Think of it as a chicken-and-egg problem. The March 2014 oceanic Kelvin wave resulted in positive (warm) SST anomalies in the eastern Pacific. However, near Indonesia and the western Pacific, SSTs have been above average, which is not typical during El Niño development. It is possible that, in order for the atmosphere to better sync up with the ocean and for this El Niño to emerge and grow, the SST anomalies in the western Pacific and Indonesia will need to become near-to-below average, strengthening the SST gradient (5). Forecasters will be watching closely for evidence of this change going forward.
