India Gears Up for Scorching Summer: What exactly is heatwave and why does it feel unbearable?

India is gearing up for a harsher summer this year, with the India Meteorological Department (IMD) predicting nearly double the usual number of heatwave days in parts of the country.

While regions like Northwest India typically see five to six heatwave days in a season, this year, the number could jump to ten or even twelve, said IMD scientist Soma Sen Roy. "We are expecting slightly above-normal heatwave conditions, especially over West and Central India," she explained, clarifying that this is a seasonal forecast, not a prediction for every single day.

With temperatures already on the rise, the IMD’s latest Seasonal Heat Outlook for March to May 2025, released on February 28, warns that most parts of the country will experience above-normal temperatures. However, the southernmost parts of Peninsular India and some areas in the Northeast might see near-normal or slightly below-normal temperatures.

Will 2025 be hotter than last year?

The IMD hasn’t made a direct comparison with 2024—India’s hottest year on record—when the country endured a staggering 554 heatwave days. However, the warning of prolonged extreme heat this year signals tough months ahead.

By definition, a heatwave occurs when the maximum temperature in plains reaches at least forty degrees Celsius or is five degrees above normal. In hilly regions, the threshold is lower, at thirty degrees Celsius.

Also Read:IMD warns of double heatwave days in Northwest India this Summer

Rising temperatures, new warnings
The coming weeks are expected to be especially hot for several states:

• Odisha: High probability of heatwave conditions between March 13 and 17

• Jharkhand: Heatwave likely from March 14 to 17

• Gangetic West Bengal: Expected to experience heatwave conditions from March 15 to 17

• South Rajasthan and North Gujarat: Possible heatwave between March 21 and 27

On March 16, heatwave alerts were already issued for Odisha, Chhattisgarh, Karnataka, and Maharashtra. In Jharkhand, seven districts saw temperatures soaring past forty degrees Celsius. Meanwhile, Karnataka’s Health Minister Dinesh Gundu Rao advised people to avoid stepping out between noon and 3 pm.

Also Read: How CM Yogi-led UP govt prepares to tackle rising mercury as IMD issues record heatwave warning

What exactly qualifies as a heatwave?

Not all hot days are classified as heatwaves. According to the IMD, a heatwave is declared when:

• The maximum temperature in plains touches forty degrees Celsius or more, or thirty degrees Celsius in hilly regions.

• The temperature is four and a half to six and a half degrees higher than normal. If it exceeds this by more than six and a half degrees, it's termed a ‘severe heatwave.’

• In coastal areas, if the departure from normal is four and a half degrees or more and the temperature crosses thirty-seven degrees Celsius, a heatwave is declared.

• If two weather stations in a region report heatwave conditions for at least two consecutive days, IMD formally announces a heatwave.

Why does extreme heat feel worse?

Beyond just high temperatures, humidity plays a crucial role in how uncomfortable a heatwave feels. When humidity is high, sweat doesn’t evaporate efficiently, making it harder for the body to cool down. Similarly, if nighttime temperatures remain high, the body doesn’t get a chance to recover from the day’s heat, adding to the discomfort.

Heatwaves in India are most common between March and June but can extend into July in some cases.

With temperatures already climbing and heatwave warnings rolling in, this summer could be one of the most challenging in recent years. Stay hydrated, avoid direct sun exposure during peak hours, and take necessary precautions to stay safe in the heat.