Northeast monsoon

In one line: The northeast monsoon is the rainy season from October to December when winds blowing from the northeast bring rain to Tamil Nadu, Puducherry, coastal Andhra Pradesh and parts of Kerala and Karnataka.

How it works

After the southwest monsoon retreats, winds over the Bay of Bengal turn to blow from the northeast. They pick up moisture over the sea and shed it on the east coast of the southern peninsula. Depressions and cyclones from the Bay add much of the rain.

Why it matters

Tamil Nadu lies in the rain shadow of the Western Ghats during the southwest monsoon, so the northeast monsoon is its main rainy season. It fills its reservoirs and tanks and supports the samba rice crop.

Why it is in the news

With the southwest monsoon withdrawing and many regions in deficit, the northeast monsoon will decide water availability in the south for the coming months.

Where to go next

• Retreating monsoon
• Low-pressure systems in the Bay of Bengal