After a week or so of warmer than normal night time temperatures over most of South India a spell of cool nights now awaits large parts of the region over the next few days. Due to the presence of the Upper Air Westerly Trough and the slightly stronger Easterly winds and associated cloudiness the nights were warmer than normal for the past few days.
The influence of the Westerly trough is slowly fading away bringing a more stable environment and clearer skies over large swathes of Peninsular India. This will play a role in the reduction of night time temperatures over the region bringing back the pleasant and cool nights.
While the interior areas of Tamil Nadu is likely to see the return of pleasant nights from tonight the coastal areas and South TN will see things change from tomorrow with cool nights the pattern for the rest of the week over most of Tamil Nadu.
As mentioned earlier with more stable atmospheric conditions prevailing we are in for a dry spell of weather over Tamil Nadu with possibly rest of February likely to see dry conditions prevail.