The India Meteorological Department (IMD) has forecast a significantly chillier winter for parts of India, anticipating higher than normal cold wave days across Northwest and Central India due to the combined influence of the Polar Vortex and continuing La Niña conditions.
❄️ Cold Wave and Temperature Projections (Dec 2025 – Feb 2026)
The IMD projects that the upcoming three-month period will be defined by below-normal temperatures in key regions:
- Cold Wave Days: Parts of Northwest, Central, and Northeast India are expected to record 1 to 4 or more cold wave days above the normal average.
- Affected States: Spatial maps specifically indicate below-normal temperatures over parts of Haryana, Rajasthan, Delhi, and Gujarat.
- Normal Average: Northwest India normally records 5-6 cold wave days during this three-month period.
- Minimum Temperatures: Normal to below-normal minimum temperatures are likely over most parts of Central India and adjoining Peninsular and Northwest India.
- Maximum Temperatures (December): Maximum or day temperatures in December are likely to be above normal over most parts of the country, except in many areas of Central India and adjoining Northwest and Peninsular India, where they are expected to be normal to below normal.
Definition of Cold Wave: A cold wave is declared if the minimum temperature is less than about 90% of the daily temperatures recorded and the minimum is less than $15^{\circ}C$. This condition must prevail for three consecutive days.
🌎 Climate Drivers: Polar Vortex and La Niña
IMD officials attribute the expected dip in temperatures and increased cold wave activity to two major climate phenomena:
- Polar Vortex Modulation:
- The Polar Vortex is a large area of low pressure and cold air that circles the Earth’s poles, strengthening in winter.
- Its modulation is expected to drive down temperatures over Northwest and Central India.
- IMD Scientist O.P. Sreejith noted that the recent below-normal temperatures in Madhya Pradesh were already linked to the Polar Vortex and La Niña.
- La Niña Conditions:
- La Niña refers to the cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean.
- It is generally associated with harsh and colder-than-usual winters in India, particularly over northern and central regions.
- La Niña is favored to continue into the Northern Hemisphere winter (December-February), with a transition to ENSO-neutral conditions most likely in January–March 2026.
🌧️ Rainfall Forecast
- Overall: Monthly rainfall over the country as a whole during December is most likely to be normal (79–121% of the Long-Period Average).
- Regional Variation: Above-normal rainfall is expected over many areas of Peninsular India and West-Central India, as well as parts of East-Central and Northeast India. The rest of the country is expected to record below-normal rainfall.