The Indo-Gangetic plain gets some rainfall in months of December and January. Why?

i. The retreating monsoon arrives in December and January in Northern Plains.

ii. Retreating monsoon is also known as winter or return of monsoon.

iii. Retreating monsoon occurs due to western disturbances moving eastward from the Mediterranean Sea.

iv. These disturbances are blocked by Himalayas and form westerlies parallel to Tibet in China.

Therefore, the Indo-Gangetic plain gets some rainfall in the months of December and January.