The mercury in Delhi shot up to 35.8 degrees Celsius, the highest so far this season, today.
The India Meteorological Department (IMD) said the city recorded a minimum of 18.5 degrees Celsius, a notch below the normal.
The air quality deteriorated slightly, moving to the middle of the moderate category (AQI 142) due to slow wind speed.
Mahesh Palawat of Skymet Weather, a private forecaster, said high humidity due to a fresh Western Disturbance is also responsible for deterioration of air quality, which had been oscillating in the good and satisfactory categories due to the 21-day lockdown imposed to contain coronavirus spread.
Cities across India have witnessed a reduction in local sources of pollution - vehicular emissions, construction dust, stack emissions etc - due to the 21-day lockdown.
Mr Palawat said light rains are expected in Delhi on Tuesday evening and the mercury is likely to touch the 40 degrees Celsius-mark between April 15 and 20.