It goes without saying for tropical areas like the plains of Tamil Nadu winter season is an understatement. Proximity to the Equator in addition to oceans on all three sides of Peninsular India modulate our temperatures. It is also essential to point out during La Nina years the winter is pretty much non existent. The frequent arrival of cloudy skies / rains associated with moisture pushed by Easterlies well into January is the reason for this. The past few days saw some light rains over parts of South TN, but overall minimum temperatures increased across the region.
With MJO expected to move further East the overall atmospheric conditions is likely to be suppressed over North Indian Ocean. This will lead to drier weather over Peninsular India along with clearer night time skies. Clear skies and dry continental winds is likely to bring down minimum temperatures gradually from tonight. Over the next week to 10 days most models indicate very little rainfall activity across the state. Except for South TN which may see occasional light drizzles dry weather is likely to prevail. The ensemble estimated rainfall range also confirms this. Almost all the district headquarters show a total rainfall range well below 1 cm.
Consequent to this we may see winter conditions to prevail over most parts of Tamil Nadu. Weather models indicate most parts of the state may see minimum temperatures stay a couple of degrees below normal. While it may not be as cool as early January most parts of Tamil Nadu except for South TN can see sub 20°C temperatures. There is a fair chance even the suburbs of Chennai may see sub 20°C from tomorrow early morning for the next week to 10 days. Clearer skies could also bring another unwanted impact. Day time temperatures across the state, particularly North TN, may stay slightly above normal. While it may not be hot certainly the warmer than normal conditions may give a feeling as though Summer has returned. Currently only places along the Peninsular West coast are in line for summer like conditions.