Heatwave gives way to high humidity in Delhi

The IMD has forecast chances of heatwave in isolated pockets of Delhi on Wednesday during the day, with drizzle and gusty winds likely towards the evening

On a day when election heat reached its peak, heatwave conditions abated marginally in the national capital on Tuesday and gave way to high relative humidity, owing to overcast skies towards late afternoon, according to the India Meteorological Department (IMD).

The minimum temperature in Delhi on Tuesday was recorded at 30.4°C, which was three notches above normal and the same as that on Monday. (Raj K Raj/HT Photo)

While the clouds brought down the maximum temperature, they raised the relative humidity and Safdarjung station, which is taken as representative of Delhi’s weather, recorded a maximum of 43.8°C, four degrees above normal. It was 44.6°C a day earlier.

The IMD said the impact of a western disturbance, which is currently influencing northwest India, is continuing in the region, and the moisture has combined with high temperature to form thunderclouds.

The IMD has forecast chances of heatwave in isolated pockets of Delhi on Wednesday during the day, with drizzle and gusty winds likely towards the evening. Despite cloudiness on Tuesday, no rain was recorded at any weather station in Delhi, said the IMD officials.

Delhi’s relative humidity oscillated between 26% and 64% through the day. And this high humidity gave Delhi a heat index (HI) or ‘real feel’ of 48.6°C. The HI was 46°C a day earlier.

A wet-bulb temperature of 32°C or higher makes it difficult for even fit and acclimatised people to work outdoors for long and at a wet-bulb temperature of 35°C — the maximum threshold — humans can no longer regulate body temperatures, leading to heat strokes and potential collapse.

In Delhi, wet bulb readings tend to be over 30°C, usually in July and early August, when temperatures are high and there is moisture intrusion, due to the southwest monsoon, said weather scientists.

“We can expect similar weather to continue over the next few days, but there are chances of isolated dust storms and drizzle towards the evening and night hours. This is likely on Wednesday and Thursday too,” said an IMD official, asking not to be named.

Isolated heatwave conditions were recorded in Delhi on Tuesday. The highest maximum temperature in Delhi was 46.4°C at north Delhi’s Narela. A day earlier, it was 46.9°C at both Najafgarh and Narela.

According to IMD, a heatwave day is one when the maximum temperature is over 40°C, while also being 4.5 degrees or more above normal. Parts of Delhi have been recording heatwave conditions since May 25.

The minimum temperature in Delhi on Tuesday was recorded at 30.4°C, which was three notches above normal and the same as that on Monday. The minimum is expected to hover between 30°C and 31°C over the next three days, said the IMD.