The India Meteorological Department (IMD) has issued a heatwave alert for Mumbai, Thane and other neighbouring districts in Maharashtra’s Konkan region on Tuesday and Wednesday. The IMD said on Tuesday the temperatures are likely to be in the range of 37 to 38 degrees Celsius for the next two days. Heatwave alert has been issued for Mumbai, Thane, Raigad and Ratnagiri for February 25 and 26.
This comes at a time when already Mumbai is scorching under maximum temperature levels exceeding the normal range. Mumbai on Monday recorded the highest maximum daytime temperature in the past five years in February 2025 with 38.4 degrees, which is 6.4 degrees above normal as per the IMD’s Santacruz observatory. The IMD’s coastal observatory at Colaba recorded a maximum temperature of 36.8 degrees on Monday, which was also 6.2 degrees above normal.
What is heatwave?
According to the World Meteorological Organization (WMO), “A heatwave can be defined as a period where local excess heat accumulates over a sequence of unusually hot days and nights. Heatwaves consist of period of abnormally hot weather that can last from a few days to months where the maximum and minimum temperatures are unusually high to a location. The minimum temperature is as important as the maximum temperature, as cooler nights allow the body to recover and if the nights are unusually hot, higher temperatures will be reached earlier in the day and last for longer.”
As a result of climate change, heat waves are becoming longer, more frequent and more severe says the United Nations Children’s Fund (UNICEF).
What causes a heatwave?
Heat waves result from warm air being trapped in the atmosphere and are a natural weather phenomenon. Heat waves are increasing in intensity and frequency due to climate change, resulting from greenhouse gas emissions that are trapping the heat for longer.
Effect of heatwaves
“Heatwaves amplify many risks, such as health-related or economic risks, including increased human mortality, drought and water quality, wildfire and smoke, power shortages and agricultural losses. Multiple risks interact with heatwaves such as droughts, fire weather, flash flooding and air pollution which have compounding impacts for people and nature,” the WMO explains.
Heatwaves impact human health and well-being, public safety and infrastructure, and the natural environment. Adverse impacts of heatwave include agricultural productivity, labour productivity, water & sanitation, critical infrastructure damage, wildlife and animal deaths, biodiversity and outdoor exercise & exposure.
Effect of Heatwaves on the Human Body
Heatwaves have a negative impact on the human body which can lead to various health problems like heat exhaustion, heatstroke, and dehydration. Heatwaves can also worsen chronic conditions even causing death.
Children, older people, pregnant women and people with chronic health conditions are more vulnerable to heat-related illness and death. Apart from this, people who lack access to cooling are also at risk.
When our body is unable to regulate its temperature, it can fall prey to medical emergencies such as heat exhaustion and heatstroke. In humid weather conditions, excessive Sweating can lead to dehydration, which in turn results in weakness and even cause a person to faint.
Children’s bodies have more trouble regulating temperature than those of adults. Heatwaves can be hazardous for babies and children, and dehydration in children can be dangerous.
Pregnant women are at greater risk as well. Too much heat and dehydration can put the baby at higher risk of low birthweight, early birth and even stillbirth. Pregnant women themselves can be negatively affected and go into early labour, as well as develop gestational diabetes and hypertension due to heatwaves.
Heatwaves might also lead to heart attacks. This is because the human body’s attempt to cool itself can strain the heart. This can trigger heart attacks in people with existing heart conditions. Heat can also put pressure on our kidneys, leading to acute kidney injury.
Death due to Heatwaves
According to the World Health Organization (WHO), heatwaves, or heat and hot weather which lasts for several days, can impact the society substantially, including leading to heat-related deaths. Heatwaves are among the most dangerous of natural hazards, but rarely receive adequate attention because their death tolls and destruction are not always immediately obvious.
A study found that from 2000–2019 approximately 489 000 heat-related deaths occurred each year, including more than 70 000 who died during the 2003 heatwave in Europe. Between 2000 and 2016, the number of people exposed to heatwaves increased by around 125 million.
Between March and June 2024, India experienced record-breaking temperatures, with 37 cities surpassing 45 degrees Celsius. While the Union Ministry of Health and Family Welfare reported 360 heatstroke deaths, a report titled ‘Struck by Heat: A News Analysis of Heatstroke Deaths in India in 2024’ was released by the non-profit HeatWatch pointed out a significantly higher toll of 733 deaths and over 40,000 heatstroke cases across 17 Indian states.
During the 2024 Lok Sabha elections, heat mitigation protocols were allegedly neglected, leading to avoidable deaths. In Uttar Pradesh alone, 33 polling officers reportedly died from heatstroke due to the lack of cooling facilities at polling stations, reports Down to Earth.
How to stay safe during heatwaves
Avoid venturing outdoors especially during the afternoon when the temperature is the highest
Stay hydrated, drink a lot of water at regular intervals
If you are feeling tired while being outdoors during the hottest parts of the day, rest in the shade
While venturing out, use sunscreen lotion, try to stay in the shade and cover your head with a hat or umbrella for protection.
If you are stepping outdoors, carry a water bottle and hand towel.
Keep an emergency kit at home that contains oral rehydration salt (ORS) packets, a thermometer, water bottles, towels or cloths to wet for cooling
During a heatwave, wear light and loose clothes especially those made of cotton because it helps reduce heat rashes and absorbs sweating. Similarly, use cotton bed sheets at home.
Seek medical help if you feel unwell
Keep your home cool by closing the curtains during the hottest parts of the day and opening windows at night time to cool down the house
Do not let your children play outside for long hours during a heatwave condition
Do not leave infants and children in closed spaces without ventilation, such as cars or rooms with closed windows
Keep your child hydrated. Children aged 6 months and above should be made to drink water regularly throughout the day
Breastfeeding mothers should drink plenty of water as dehydration can affect them and the child in the womb. It also affects breastmilk production in expecting mothers
Provide shade and water to stray animals, they are helpless
Responsibility of the Government during Heatwave
Ahead of a heatwave, the government can alert citizens by:
Issuing early warnings through weather forecasts through bodies like the India Meteorological Department (IMD)
Creating heat action plans
Raising public awareness through campaigns talking about heat-related risks
Establishing cooling centres
Ensuring access to clean drinking water
Coordinating with healthcare facilities to effectively manage heatstroke cases, particularly among those who are more vulnerable like the children and elderly, those without a shelter
Making provision for stray animals
The government can take proactive measures like urban planning strategies to mitigate the urban heat island effect by planting trees and using heat-resistant building materials
