Mumbai weather updates: ‘Nothing really works against this heat’

Traffic constable Honaji More sips water at Mahalaxmi signal to cope with the heat. Pics/Ashish Raje

Once known for its humid but relatively stable climate, Mumbai is now battling an escalating heat crisis. The city is witnessing a surge in heatwave days, compounded by the Urban Heat Island (UHI) effect - an alarming phenomenon caused by dense construction, disappearing green cover, and heat-retaining infrastructure. Together, they've turned Mumbai into a furnace, with the most crowded areas suffering the worst.

Road workers continue digging work under the blazing sun at Kalanagar, Bandra East

To understand the human cost of this rising heat, mid-day spoke to those who spend long hours outdoors, braving the blistering sun: traffic police, dabbawalas, postmen, and residents of informal settlements.

Railway porters rest in the shade near Bandra Terminus, trying to escape the blazing sun. Pics/Ashish Raje

Hotter every year

A Swiggy delivery rider on duty fully covered up against the harsh afternoon sun at Mahalaxmi

In 2024 alone, Mumbai experienced more than 10 heatwave days - a massive leap from the one or two recorded annually just a decade ago. Urbanisation has amplified the UHI effect, pushing temperatures in congested neighbourhoods 3-5°C higher than less crowded areas. The result? Sweltering nights, relentless heat, and growing health risks for the city's most vulnerable.

No aid for labourers

A water vendor waits at the Bandstand promenade in Bandra, on March 1. Pic/Ashish Raje

Speaking about those worst-hit by the rising heat, housing rights activist Bilal Khan, convenor of Ghar Bachao, Ghar Banao Andolan, told mid-day: "Heatwaves are now routine. Slum residents, transit camp dwellers, and daily wage labourers waiting at nakas are worst affected. The government must act. Why are gardens shut during peak hours when people could use them for relief?"

A porter hauls luggage outside the parcel section at Bandra Terminus under the afternoon sun. Pic/Ashish Raje

Khan asked why Mumbai still lacks a dedicated heat action plan. "If Ahmedabad can do it, why not Mumbai or Maharashtra? Development must be inclusive and consistent. We need policies that prioritise the most vulnerable."

Bilal Khan, housing rights activist, convenor of Ghar Bachao, Ghar Banao Andolan

On the frontline

Traffic police are among the hardest hit. A traffic constable posted in Borivli said, "We're used to heat, but this is different. There are no instructions or allowances for breaks, and we can't leave our posts."

A police constable finds shade under an umbrella at Mahalaxmi amid the unrelenting afternoon heat. Pic/Ashish Raje

Honaji More, a constable stationed in Mahalaxmi, added: "Even with water breaks, we feel dizzy and fatigued. Our shifts are from 7 am to 3 pm and 3 pm to 11 pm. I'm on the second shift - standing in the sun is draining, but duty comes first."

Handcart workers hydrate themselves at Abdul Rehman Street as temperatures soar. Pic/Anurag Ahire

Dabbawalas, Mumbai's tiffin carriers, are also feeling the burn. "We receive no official assistance," said Ulhas Muke, president of the Nutan Mumbai Tiffin Box Suppliers Charity Trust. "Still, staying home isn't an option. We carry lemon juice and electrolytes, but dehydration is constant."

Ulhas Muke, president of the Nutan Mumbai Tiffin Box Suppliers Charity Trust

Muke added that some elected representatives have helped by providing shaded resting spots. "But most dabbawalas, many of them over 50, still cycle through heatwave conditions daily."

Ritesh Andre, who oversees the dabbawala operations and is a descendant of the city's first tiffin carrier, added: "We've formed support teams to help anyone who falls ill. We're also shifting more of the load to our younger members to protect the older ones."

Postmen sort letters while seated under the Lower Parel bridge to escape the heat. Pic/Ashish Raje

Postmen face similar struggles. Sangeeta Shinde, a postwoman in Malad East, said, "From 11 am to 4 pm, we're out in the field. We walk 4-5 km daily, often climbing stairs in buildings with no lifts. Caps and lemon juice help a little, but nothing really works against this heat." Another postman in Andheri said, "By noon, our uniforms feel like they're on fire. We try to move faster, but it's tough."

Trapped inside

For those living in tin-roofed slums, the heat doesn't end with the workday. In places like Dharavi, Govandi, Mankhurd, and Kurla, homes become ovens.

Vasanti Pawar at her house at Chitra Chawl in the Nehru Nagar slum, in Vile Parle West. Pic/Satej Shinde

Vasanti Pawar, 67, a resident of Nehru Nagar, Juhu, said, "The heat has become unbearable in the last few years. We can't sleep at night or stay indoors during the day. One fan is all we have - we can't afford an AC."

Her home is now surrounded by taller buildings, blocking airflow. "We're suffocating. The heat inside is worse than outside," said Shabana Sheikh from Mankhurd. "We pour water on the roof, but it doesn't help," she further added.

Vasanti Pawar, 67, a resident of Nehru Nagar, Juhu

Ahmed Khan in Kurla added, "My mother has asthma. A fan only blows around hot air - we can't afford better."

New data confirms

UHI impact
A recent study by Respirer Living Sciences shows stark temperature variations across Mumbai. Between March 1 and March 22, 2025:
>> Vasai West recorded 33.5°C
>> Ghatkopar hit 33.3°C
>> Colaba reached 32.4°C
>> Powai, in contrast, was a much cooler 20.4°C
That's a 13.1°C difference within the same city.

What causes UHI?
Densely packed concrete buildings, lack of trees, and high pollution - all of which trap heat and worsen microclimate conditions. "Micro-climate zones are now forming within Mumbai," said Ronak Sutaria, founder of Respirer. "The consequences - health stress, energy strain, and inequality - are growing." He called for zone-specific heat forecasting and localised solutions: "Mumbai isn't one uniform city. We need green infrastructure, reflective roofs, and smart planning at a neighbourhood level."

Heat divide widens
An analysis of 22 CPCB stations revealed alarming temperature gaps across Mumbai. Vasai West topped the charts with an average of 33.5°C, while Powai remained much cooler at 20.4°C - a staggering 13.1°C difference. Ghatkopar recorded 33.3°C, Colaba 32.4°C, Chakala (Andheri East) 23.4°C, and Chembur 25.5°C. "These disparities reflect the rise of microclimates within the city," said climate researcher Aditya Sutaria. "They have deep implications for health, energy use, and equity."

Colaba no more a ‘cool zone'
Historically cooled by sea breeze, Colaba is heating up.

Zone-specific forecasting
Sutaria stressed the need for hyperlocal planning: "Mumbai cannot be treated as one thermal unit. Solutions like reflective roofs, green cover, and smart architecture must be tailored zone by zone."

March 2025

Heatwave preview
Between March 6-11, Mumbai saw near-40°C highs due to strong easterlies and a delayed sea breeze. March 9 and 10 touched 37°C. Authorities issued warnings for March 18 as more spikes loomed.

Repeat patterns
A 2024 study by Respirer Living Sciences had already flagged similar temperature gaps - Borivli East was 13°C cooler than concrete-heavy Worli.

The bigger picture
"Heat stress isn't hitting everyone equally," said Andheri resident Mrunalini Kamat. "We need neighbourhood-specific interventions to protect people - especially children and the elderly."

Sutaria added: "These sustained heat spells before summer even starts show we can't delay action on the Urban Heat Island effect."

Health crisis in the making
Hospitals are already reporting more heatstroke and dehydration cases, especially in low-income areas. Children and the elderly are at greatest risk.Yet climate adaptation remains missing in urban planning. Experts urge immediate action - shaded public areas, cool roofs, and community cooling centres.

Local efforts not enough
Some communities have begun installing cool roofs and planting trees, but experts say resilience must scale fast.

Mumbai's heatwave trends

Heatwave criteria:
>> Standard: Max temp > 37°C or 4.5-6.4°C above normal
>> Severe: Max temp ≥ 6.5°C above normal

Heatwaves (1977-2025):
>> Total since 1977: 13
>> Last 15 years: 8, showing a sharp rise
>> Severe events: 2004, 2011, 2022, 2023, 2024, 2025

Warming trend:
>> Decadal rise (1973-2020): +0.25°C
>> Annual increase:
>> 1973-1998: +0.004°C
>> 1999-2008: +0.011°C
>> 2009-2020: +0.042°C

MCAP insight: Urbanisation is intensifying heat, especially at night. "The evening and nighttime spikes point to a hyperlocal, man-made phenomenon," notes the report.

(IMD & MCAP data)