Forecasting models "failed" to predict the extreme weather event that took Delhi residents by surprise early Friday, resulting in a record 228.1 mm of rainfall, meteorologists said.
This amount is more than three times the June average of 74.1 mm and the highest for the month since 1936.
An IMD official explained that the monsoon winds interacted with the remnants of a western disturbance, causing heavy rains in Delhi, Himachal Pradesh, and Jammu and Kashmir.
Independent scientists suggested that a thunderstorm over North Delhi could have triggered the torrential rains.
On June 26, the IMD had predicted only light to moderate rain and thunderstorms with gusty winds for Friday (June 28).
On Thursday afternoon, the Met office noted that a trough extended from a cyclonic circulation over central Gujarat to west Bihar in the lower tropospheric levels.
In the weekly weather briefing uploaded on the IMD's YouTube page, scientist Soma Sen Roy said this trough was pumping moisture into n
