Last few days the temperatures have gradually come down in South India, initially the interior parts of Peninsular India saw night time minimum temperatures drop to a couple of degrees below normal under dry atmospheric conditions along with the strengthening land winds. The last couple of days have also seen coastal areas of Tamil Nadu witness an appreciable temperature drop. Early today morning the IMD Observatory at Chennai Airport recorded 19.2ºC at 5:30 AM, while the observatory at Nungambakkam recorded 19.4ºC both the observatories recording their coldest nights of 2021.
Weather models indicate similar conditions to persist for the next couple of days with places in North Interior Tamil Nadu & adjoining areas of Peninsular India witnessing temperatures in the region of 15ºC. While places closer to the coast may marginally dip lower than 20ºC places about 20 to 50 kms from the coast line will possibly see night time minimum temperatures drop to around 17 / 18ºC including the Western Suburbs of Chennai. Tonight parts of interior Delta could see the night time minimum temperatures stay 3 / 4 degrees below normal going by weather model outlooks.
Until the day after Christmas these conditions are likely to persist before the gradual return of the Easterlies will bring back an increase in temperatures due to not only the modulation effect of Bay of Bengal but also the cloudiness associated with the returning Easterlies that is likely to trap the Sun’s heat radiated by Earth compared to clearer skies during dry weather conditions which allows the radiated heat to be sent back to atmosphere. Not to forget this spell of Easterlies will also increase the humidity over coastal areas.