Today, Kolkata recorded first rain spell of the season. Both observatories of Kolkata, Alipur and Dumdum airport recorded 1mm of rainfall. In fact, many areas of Kolkata and suburbs recorded intense rain and thundershower activities with lightning strikes during morning hours today. This is the first rainy spell for Kolkata of 2021. Kolkata received the last spell of rain on November 11 recording 23mm of rain. Since then weather of Kolkata remained dry.
December is the least rainy month for Kolkata with the monthly average of just 3.2 mm. Monthly average rainfall over Kolkata for January is 10.4mm and for February it is 20.9mm. Kolkata has received single-digit January rainfall in 4 years during the last decade. February 2018 remained dry with no rain activities in Kolkata. Record rainfall in the month of February for Kolkata is 83.5 mm which occurred on February 25th in 2016.
The formation of a low-pressure area in the north Bay of Bengal is very rare in winters. Gangetic West Bengal, as well as Kolkata, usually receives rainfall in winters due to the formation of a Confluence zone or due to the formation of a trough. A trough is extending from sub-Himalayan West Bengal to south Chhattisgarh and a cyclonic circulation is persisting. The combined effect of these weather parameters is responsible for these scattered rain and thundershower activities over East India including Gangetic West Bengal and Kolkata. Now we expect whether to go dry once again over Kolkata, and minimum temperatures may drop by 2 to 3 degrees in the next couple of days.