The four seasons: cold weather, hot weather, rainy season and retreating monsoon
India's year turns through four seasons: cold weather, hot weather, the advancing south-west monsoon and the retreating monsoon, each with its own winds and weather.
The cycle of seasons
- back to Cold weather season (December to February)
Cold weather season (December to February)
- Temperature falls from south to north: about 12 °C to 15 °C in the north and about 25 °C in the south.
- Frost is common in the north and north-west. The higher Himalayas get snowfall.
- Western disturbances bring light rain to the north-west, which is very useful for rabi crops.
- The north-east trade winds blow from land to sea, so most of India is dry.
- Part of these winds crosses the Bay of Bengal, picks up moisture and gives rain to the Tamil Nadu coast.
- The north has clear skies, low temperatures and low humidity.
Hot weather season (March to May)
- Temperatures rise from the end of February. The plains, western India and the central peninsula get very hot.
- A long low pressure trough forms from Jaisalmer in western Rajasthan to Jharkhand and Odisha.
- Afternoon dust storms are common in north-west India.
- The loo: very hot, dry winds over the northern plains. Exposure can cause heat stroke.
- Local thunderstorms bring violent winds, heavy downpours and often hail. In West Bengal they are called Kaal Baisakhi, the calamity of the month of Baisakh.
- Near the end of summer, pre-monsoon showers in Kerala and Karnataka help mangoes ripen early. They are called mango showers.
Advancing south-west monsoon season (June to September)
- People wait for the rains to bring relief from the heat. Farmers prepare their fields for kharif crops.
- By the end of May the trough over north India deepens. Moist winds blow from the south-west at about 30 km per hour.
- They reach the Andaman and Nicobar Islands in late May and Kerala in the first week of June. Then they split into the Arabian Sea and Bay of Bengal branches.
- Rain comes in wet spells with breaks between them. Temperatures drop by 5 °C to 8 °C.
- Some areas face floods while others face drought in the same season.
Retreating monsoon season (October and November)
- Temperatures start falling in north India. The monsoonal trough weakens and is replaced by high pressure.
- The south-west winds weaken and withdraw from the northern plains by November.
- In October, high temperature and moist ground make the northern plains hot and humid. This oppressive weather is called October heat.
- By the end of October nights become pleasant.
- The low pressure shifts to the Bay of Bengal, where cyclones form. They strike the coasts of Odisha, Andhra Pradesh and Tamil Nadu, especially the deltas of the Mahanadi, Godavari and Krishna.
On the map
- Loo: blows over the northern plains of Punjab, Haryana, Rajasthan and Uttar Pradesh in summer.
- Kaal Baisakhi: storms of the hot season in West Bengal.
- Mango showers: pre-monsoon rain on the coasts of Kerala and Karnataka.
- Tamil Nadu (Coromandel) coast: gets rain from north-east winds in the retreating and winter seasons.
- Cyclone coasts: Odisha, Andhra Pradesh and Tamil Nadu on the Bay of Bengal, in October and November.
- Snowfall: the higher Himalayas in the cold season.
In Chennai, November is the wettest month, while Delhi is dry and turning cool. Each October and November, weather warnings tell coastal Odisha and Andhra Pradesh to watch for cyclones from the Bay of Bengal.
3 marks: “What is the weather like in India from December to February? Give three features.” December to February; temperature falls from south to north (12 to 15 °C in the north, about 25 °C in the south); frost in the north and snow on the Himalayas; dry north-east winds; light rain from western disturbances helps rabi crops; the Tamil Nadu coast gets rain. Any three.
2 marks: “What is October heat? Why does it occur?” In October, after the monsoon withdraws, temperatures are still high and the ground is moist. This makes the northern plains hot and humid, and the oppressive weather is called October heat.
1 marks: “What are the hot, dry summer winds of the northern plains called?” The loo.
Calendar code: D-J-F cold, M-A-M hot, J-J-A-S rains, O-N retreat.