Climate of India — Part 2: Seasons, local winds and climate data

Hot weather (March–May): temperatures rise northward; low pressure over the north-west; dry hot winds; local storms (next slide). South-west monsoon (June–September): onset in Kerala about 1 June; most of India gets 75–90% of its annual rain; rainfall is uncertain and uneven — with breaks of dry spells, heavy rain on windward slopes, and decreasing rain from east to west in the north. Temperatures drop slightly when the rains arrive, but humidity is high.

Retreating monsoon (October–November): the sun moves south, the low pressure over the north weakens and the monsoon withdraws; clear skies and high humidity cause oppressive “October heat”. Winds over the Bay of Bengal now blow from the north-east, pick up moisture over the bay and bring heavy rain to the Tamil Nadu coast (which lies in the rain-shadow of the south-west monsoon). Tropical cyclones from the Bay strike the east coast. Cold weather (December–February): clear, cool, dry; frost in the north-west; snow in the Himalayas; rain from western disturbances in Punjab and Haryana (useful for wheat).