The national capital Delhi would see the ongoing heatwave peak on Sunday with the maximum temperature settling at above 46*C in many areas, according to weather forecasters.
The maximum temperature at the Safdarjung Observatory, Delhi's base station, is likely to rise to 45*C on Sunday.
The IMD said a thunderstorm or a dust storm is likely in the national capital on Monday.
Battered by hot and dry westerly winds, Delhi on Saturday saw its hottest day of the season with the city's base Safdarjung observatory recording the maximum temperature of 44.2*C. Mungeshpur in Delhi recorded the maximum tempeature of 47.2*C and mercury at Najafgarh soared to 47*C.
Weather forecasters said the heatwave spell would worsen on Sunday.
"Hot and dry westerly winds sweeping the Delhi-NCR region will push the maximum further up. It is likely to hit the 45-degree mark at Safdarjung on Sunday," said Mahesh Palawat, Vice President (Meteorology and Climate Change), Skymet, a private weather forecasting agency.
An "orange" alert has been issued to caution people about a severe heatwave. The IMD uses four colour codes — green (no action needed), yellow (watch and stay updated), orange (be prepared) and red (take action) — for weather warning.
The IMD said the heatwave could lead to "moderate" health concerns for vulnerable people — infants, elderly, people with chronic diseases — in affected areas.
It said, "Hence people of these regions should avoid heat exposure, wear lightweight, light-coloured, loose, cotton clothes and cover the head by use of cloth, hat or umbrella etc."
"A cyclonic circulation over Punjab and Haryana will induce pre-monsoon activity which will provide some relief from the intense heat on Monday and Tuesday," said Skymet's Palawat.
With scanty rains owing to feeble Western Disturbances, Delhi had recorded its second hottest April this year since 1951 with a monthly average maximum temperature of 40.2 degrees Celsius.
Moreover, cloudy skies and thunder may provide some relief from the intense heat in the upcoming week.
The monsoon is expected to arrive in Andaman and Nicobar islands on Sunday ahead of schedule. It would take it three to four weeks to spread to other parts of the country after hitting Andaman and Nicobar islands. Further relief from the heat is expected then.
(With PTI inputs)