Tamil Nadu has a tropical climate with no wild swing between summer and winter temperatures.
Summer: April and May are the hottest months with
the mercury often soaring above the 40ºC (108.75 F approx.) mark.
Even the coastal regions are warm and humid during the summers, but with
the nightfall, however, cool sea breeze brings some respite. Summer
temperatures are quite equable at the foothills of the ghats. But the most
pleasant are the hill stations where the maximum temperature rarely rises
above mid twenties in summer.
Rainy: In Tamil Nadu the rainy season is between October and December when the Northeast monsoon brings rain in spurts. The average annual rainfall, falling mainly between October and December, ranges between 25 and 75 inches. The most precipitation falls in the Nilgiris and other hill areas.
Winter: Winter falls between November-February during which, the mercury hardly falls below 20°C (54 F approx.), except in the hill stations. The winter monsoons of Tamil Nadu occur in the months of October to December. The lowest temperatures are recorded during December and January.
Summer: 43°C to 18°C (116 F - 48 F
Winter: 35°C to 17°C (95.15 F - 46.21 F approx.)
November - February
Lightweight cottons and linens in summer and tourists visiting the hill stations have to carry woollen clothes along, as the climate is pleasantly cool in the hill stations.