12-day heatwave streak in Delhi abates after light rain

The weather fluctuations also dipped Delhi’s minimum by nearly six degrees to 24.6°C, three degrees below normal

Light to moderate rain combined with squally winds effectively broke the 12-day streak of heatwave conditions in the Capital and slashed the maximum temperature by two to three degrees in most places, the India Meteorological Department (IMD) said. No weather station in Delhi recorded a heatwave on Thursday, IMD added.

IMD data showed that till 8.30 am on Thursday, Ayanagar recorded 3.8mm of rainfall. (Arvind Yadav/HT Photo)

A dust storm began to gather pace late on Wednesday night giving way to light to moderate showers in parts of the city, bringing the mercury down to 41.2°C on Thursday at Safdarjung, representative of Delhi’s weather. This was 2.8 degrees below Wednesday’s 44°C and only a degree above normal.

Additionally, cool northwesterly winds prevailed during the daytime, reining in the maximum from spiking too high, weather officials said, while predicting a change in the wind direction to dry westerlies once again on Friday. This could lead to a marginal rise in the maximum temperature, they added.

The weather fluctuations also dipped Delhi’s minimum by nearly six degrees to 24.6°C, three degrees below normal. It was 31°C a day earlier.

“Parts of Delhi received light rain and recorded gusty winds up to 40 km/hour late on Wednesday night and in the early hours of Thursday, which made for a cool night. During the day, we also had northeasterly winds, strong wind speed, and partially cloudy skies, which all helped keep the temperatures in check,” said an IMD official.

IMD data showed that till 8.30 am on Thursday, Ayanagar recorded 3.8mm of rainfall; Lodhi Road 1mm; Narela and Pitampura 1.5mm each; Pusa 1mm and Rajghat 9mm. Safdarjung recorded 1.2mm of rainfall. The highest maximum temperature across the city was 44.6°C at Najafgarh, four degrees above normal.

Delhi’s relative humidity oscillated between 22 and 72% between Wednesday and Thursday. However, Thursday’s Heat Index (HI) or “real feel” was 41.9°C. It was 46°C a day earlier.

Delhi’s wet bulb temperature, an indicator of comfort level outdoors, was between 24.9°C and 27°C. The highest wet bulb a day earlier was 27.1°C. A wet-bulb temperature of 32°C or higher makes it difficult for people to work outdoors for long and a wet-bulb temperature of 35°C — the maximum threshold — makes it difficult to regulate body temperatures, leading to heatstrokes and potential collapse. In Delhi, this tends to be over 30°C in July and early August, when temperatures are high coupled with moisture intrusion due to the southwest monsoon.

Before the brief respite on Thursday, Delhi recorded a series of heatwave days between May 17 to 20 at different weather stations. At Safdarjung, six such days were recorded consecutively between May 26 and 31. The last time Delhi had such a spell was six consecutive days at Safdarjung between May 19 and May 24, 2013. The weather agency classifies it as a “heatwave” when the maximum temperature is over 40°C, while also being over 4.5°C above normal. No weather station in Delhi met this criteria on Thursday.

Thursday’s was the lowest maximum since May 23, when it was 41°C. Both maximum and minimum temperatures are forecast to rise again on Friday. The maximum will be around 43°C and the minimum 29°C, owing to dry westerlies.

“This change in wind direction may make the day warmer. However, there are still chances of isolated parts of Delhi recording a drizzle, along with gusty winds,” the official quoted above added.