This season extends from the middle of November to the middle of March. The coldest months are January and February.
The daily temperature remains below 21°C. At some places the temperature drops below freezing point.
The westerly jet stream sweeps cyclones and depressions from the Mediterranean Sea and Persian Gulf to the north-west of India. These cyclones and depressions are called Western Disturbances.
The number ranges from 4 to 5 in the season. The western disturbances come from December to February and cause rainfall in the northern plain of India and snowfall in the Himalayan area.
The amount of rainfall decreases from the west to the cast. It is usually 50-55 cm in the west but is reduced to 18-25 cm in the east. This rainfall is very useful for the Rabi crops. Even in north-east India (Assam, Arunachal) this rainfall is to the tune of 50 cm.
The Climatic Conditions in the Peninsula.
The winter season is almost nonexistent in the coastal area of South India. In January, the highest temperature at Thirvivananthapuram is about 31°C which is nearly the temperature of June.
The eastern coast of T.N. gets rainfall from the north-eastern winds. These winds are dry but while crossing over the Bay of Bengal, absorb a lot of humidity and cause rainfall in T.N.