After red alert, IMD issues heatwave warning for Delhi, parts of north India till May 25. Details here

IMD heatwave alert: The India Meterological Department (IMD) on Monday warned of heat wave to severe heat wave conditions in Delhi and other parts of north India for the next three days. The weather office also warned of sweltering weather conditions in parts of Punjab, Haryana, Chandigarh, West Bengal and in some pockets of western Uttar Pradesh, eastern Rajasthan as well as northwestern Madhya Pradesh till May 25.

Heatwave conditions are also likely to prevail in parts of Himachal Pradesh, Uttarakhand, east Madhya Pradesh, Odisha, Gujarat, Saurashtra, Kutch and Vidarbha till May 25, as per the Met department. The IMD also predicted warm night conditions in western Uttar Pradesh, Gujarat and Rajasthan till May 25.

Hot and humid weather is also very likely to prevail over Konkan & Goa, Bihar and Jharkhand for the next 3 days. The heatwave warning comes a day after the weather office issued a 'red alert' for the next 5 days due to heat wave to severe heat wave conditions in Delhi.

On Monday, the maximum temperature teetered around 44 degrees Celsius to 47 degrees Celsius in most places over Delhi, Haryana, and Chandigarh.  Temperatures ranged between 40-44 degrees Celsius in parts of Uttar Pradesh, Punjab, west Madhya Pradesh, east Madhya Pradesh, Gujarat, Madhya Maharashtra, Marathwada, Vidarbha, Saurashtra and Kutch on the same day.

"These were above normal by 4-6 degrees Celsius at many places over Delhi and above normal by 2-4 degrees Celsius over many parts of Punjab, Haryana-Chandigarh; in isolated pockets of Rajasthan, Saurashtra & Kutch and West Uttar Pradesh," the IMD said.

Heat wave definition, criteria, maximum temperature

The India Meteorological Department (IMD) defines heat wave as a condition of air temperature "which becomes fatal to human body when exposed." The IMD declares a heat wave when the maximum temperature crosses 40 degrees Celsius in plains and at least 30 degrees Celsius or more in hilly regions.

In case of a heat wave, the departure from normal temperature is 4.5-6.4 degrees Celsius. In a severe heat wave, the departure from normal temperature is above 6.4 degrees Celsius for at least 2 days.

Based on actual maximum temperatures, the weather office declares a heat wave when actual maximum temperature is either equal to or more than 45 degrees Celsius for at least 2 days. A severe Heat Wave is declared when actual maximum temperature is equal to or above 47 degrees Celsius for 2 days or more.