After a scorching day that saw the mercury touch 40.5°C, thunderstorms, rain and strong winds cooled large parts of Delhi on Thursday evening, Thunderstorms and gusty winds touching 91kmph caused temperatures to plunge by 9°C to 19°C in parts of Delhi within hours.Strong winds accompanied the rain across much of the city and adjoining areas. (Ajay Aggarwal/ HT)The India Meteorological Department (IMD) upgraded a yellow alert issued for the city in the morning to an orange alert around 7pm as thunderstorm activity intensified across the region.Till 5.30pm, Ayanagar recorded the highest rainfall at 27.6mm, followed by Mayur Vihar at 24.5mm and Ridge at 19mm. Pragati Maidan received 12.8mm of rain, Palam 10.7mm, Pusa 8mm, Lodhi Road 4mm and Najafgarh 1.5mm. Safdarjung, considered representative of Delhi’s weather, recorded only 1.6mm of rainfall, while Pitampura received 0.5mm.IMD data showed a sharp drop in temperatures in several areas following the thunderstorms. Ayanagar recorded the steepest decline, with temperatures falling 19°C from 41°C to 22.7°C. Dadri recorded a drop of 15.7°C, while Pushp Vihar and Mayur Vihar saw temperatures fall by around 14°C to 15°C. At Safdarjung, the temperature dropped 9°C from 40°C to 31°C.Strong winds accompanied the rain across much of the city and adjoining areas. The highest wind speed was recorded at Dadri at 91kmph, followed by Palam at 65kmph. Safdarjung recorded a maximum wind speed of 36kmph.Despite the evening rain, Delhi’s maximum temperature for the day stood at 40.5°C, while the minimum temperature was recorded at 29.7°C.The IMD has issued a yellow alert for Friday, forecasting multiple spells of light rain and thunderstorms along with a further decline in both maximum and minimum temperatures. Rain is expected to continue on Saturday as well, before temperatures begin rising again from Sunday. The maximum temperature is likely to reach 40°C to 42°C by June 9.Meanwhile, Delhi’s air quality deteriorated despite the rainfall. The city’s 24-hour average Air Quality Index (AQI) rose by 21 points from 143 on Wednesday to 164 on Thursday, remaining in the “moderate” category.