After a week of sweltering weather, Delhi was hit by a thunderstorm in the early hours of Thursday, bringing rain and gusty winds to the National Capital Region (NCR), which recorded a dip in temperature as well as a stark improvement in pollution levels, which dropped from the previous day’s “very poor” air to the “moderate” zone.Safdarjung, representative of Delhi’s weather, received 9.6mm of rainfall in the 24 hours till 8.30am on Thursday, while Ayanagar and Lodhi Road recorded 7.8mm rain each, India Meteorological Department (IMD) data showed.

With this spell of rain, Safdarjung has now received 60.4mm of rainfall so far this month — nearly twice the monthly normal mark of 30.7mm.

Thursday’s showers, accompanied by gusty winds of speeds up to 55kmph, meant Delhi’s maximum temperature dropped to 36.5 degrees Celsius (°C) — four degrees below normal for this time of the year, and 4.5 notches below Wednesday’s high of 41.1°C.

The maximum temperature in Gurugram was 38°C, while it was 37°C in Noida, Ghaziabad and Faridabad.

Delhi’s minimum, meanwhile, dropped to 21.9°C —five degrees below normal, while it was 27°C at Gurugram, Noida, Ghaziabad and Faridabad.

The IMD attributed the storm to a western disturbance affecting northwest India, but warned that the temperatures are likely to spike to around the 42-degree mark by the weekend.

“The rain and gusty winds we saw were due to the western disturbance impacting northwest India. Strong thunder clouds formed overnight, with wind speeds touching 55 km/hr at places between 3 and 4 am,” said Kuldeep Srivastava, scientist at IMD, adding that another western disturbance is expected to affect the NCR region on May 23.

“We may see some very light rain on May 23 and 24, but before that, the temperature will rise once again. It is likely to touch 42 degrees by this weekend,” he said.The rain and strong winds also helped settle pollutants which had been plaguing NCR over the last two days. According to the Central Pollution Control Board (CPCB) 24-hour national bulletin, released at 4pm, Delhi’s Air Quality Index (AQI) on Thursday was 149 — a sharp drop from the AQI reading of 336 on Wednesday.

Forecasts by the Early Warning System (EWS) for Delhi, which is used by the Commission for Air Quality Management (CAQM), showed Delhi’s air is likely to remain in the “moderate” zone on Friday and Saturday, before deteriorating to the “poor” category on Sunday.

The CPCB classifies an AQI between 0-50 as “good”, between 51 and 100 as “satisfactory”, between 101 and 200 as “moderate”, between 201 and 300 as “poor”, between 301 and 400 as “very poor”, and over 400 as “severe”.