“There will be a gradual rise in the maximum temperatures by 4 to 6 degrees Celsius and will remain between 46-48 degrees Celsius till May 19,” the Met department said.

“An upper air cyclonic circulation prevails over Northwest Uttar Pradesh and Southwest Madhya Pradesh, both of which are leading to air subsidence over the region. The warm air accumulated during the daytime is thus remaining trapped, making the nights warmer than usual,” an IMD official said.

On Tuesday, Barmer in West Rajasthan recorded 48.3 degree Celsius, making it the hottest place in the country. The city’s highest-ever May temperature — 49.9 degrees Celsius — was recorded on May 27, 2024.

Other peak May temperatures recorded in Barmer between 2015 and 2025 were 49.5 degrees Celsius on May 19, ߠ 46.9 degrees Celsius on May 28, ߢ 48.1 degrees Celsius on May 12, ߦ and 46.2 degrees Celsius on May 26, 2017.

IMD also noted unusually warm nights in Rajasthan, with minimum temperatures ranging between 26 and 31 degree Celsius. For comparison, Ranchi recorded a daytime high of 31.8 degree Celsius on Tuesday.

According to IMD, a heatwave is declared in the plains when the maximum temperature exceeds 40 degree Celsius and remains 4.5 to 6.4 degrees above normal. A “severe” heatwave is declared when the departure exceeds 6.4 degrees Celsius.

IMD also said the Southwest Monsoon is likely to advance into the Andaman Sea and southern Bay of Bengal around May 16, nearly six days ahead of its normal onset date of May 21.

“Conditions are becoming favourable for the advance of the Southwest Monsoon over parts of the South Bay of Bengal, Andaman Sea and Andaman and Nicobar islands around May 16,” the weather office said.

Meanwhile, a low-pressure area over the southwest and adjoining west-central Bay of Bengal intensified into a well-marked low-pressure area Wednesday.