Signalling the start of heatwave conditions in Delhi, the maximum temperature soared to 40.2℃ in the national capital on Monday, which was nearly five notches above normal.

However, for the MeT to declare a heatwave, the temperature must remain over 40℃ and at least 4.5℃ to 6.5℃ above normal in at least two stations in a meteorological subdivision in the plains for two consecutive days. The heatwave was declared on the second day.

The India Meteorological Department (IMD) has already issued heatwave warnings over most parts of northwest India this week. In Delhi, the main observatory at Safdarjung recorded 40.2℃ – April’s highest so far. Bu, the temperatures settled a notch higher at 41℃ at the Ridge and Ayanagar units.

Last year, the temperatures reached this high in Delhi only towards the end of April. So far, the forecast rules out warm nights for this week and indicates that temperatures are likely to settle around 19℃ to 24℃ during the night. But the days are expected to become hotter over the next three days, with temperatures likely to surge by 2℃ to 3℃. A brief respite may only arrive after April 10, following the impact of an incoming Western disturbance over the Western Himalayan region.
An illustration showing heatwave conditions in India on April 7. (Source: IMD)

India has been hit by an unusually early spell of heatwave this year leaving parts of central India and western states reeling from March 10 to 18. Another spell began in April, expanding over the western parts of the country, especially Rajasthan and Saurashtra-Kutch, where the conditions have become severe, and are likely to persist till April 9.

Barmer in Rajasthan recorded the highest maximum temperature of the day at 45.6℃, nearly 6.8℃ above normal, followed by Jaisalmer at 45.4℃, which was nearly 8℃ above normal. Gujarat’s highest was recorded at 45.3℃ in Kandla, and Chhattisgarh’s highest was at 43.5℃ in Rajnandgaon – also recording the highest departure from normal values at nearly 9.1℃.

Some parts of Haryana (Rohtak) and West Madhya Pradesh also experienced heat waves in isolated pockets on Monday. “The day’s temperature is above normal by 5℃-8℃ over most parts of Jammu and Kashmir, Himachal Pradesh, Rajasthan, Delhi, Punjab, Haryana, Chandigarh, as well as Ladadkh," said the weather department.
The IMD has already warned of an exceptionally hot summer in India this year, with above-normal heatwave days in most parts of the country. “Many parts of India typically witness four to seven heatwave days from April to June; however, this year, the number could go up to six to 10 in some areas. East-central areas are likely to be more affected," said IMD chief Dr M Mohapatra.

This follows an unusually warm start to the year, with even the average monthly temperature in March recorded 0.78℃ above the long-period average, and the hottest February since 1901, which was nearly 1.3℃ hotter than usual.