Cold wave conditions in Delhi from December 16 to 18

The India Meteorological Department (IMD) designates days as cold wave days in the plains if the minimum temperature is 10 degree Celsius or lower and at the same time 4.5 degrees or more below the normal minimum temperature for the day for two consecutive days.

Delhi woke up to the coldest day in December, as the minimum temperature dropped to 4.1 degree Celsius on Tuesday morning. The capital is likely to witness cold wave conditions from December 16 to 18, according to forecasts made by the Regional Meteorological Center (RMC) in Delhi. The India Meteorological Department (IMD) designates days as cold wave days in the plains if the minimum temperature is 10 degree Celsius or lower and at the same time 4.5 degrees or more below the normal minimum temperature for the day for two consecutive days.

A person using an electric scooter inquires from police personnel manning barricades on Rajpath near India Gate in New Delhi on Saturday, December 12, 2020. (Sanchit Khanna/HT PHOTO)

North-western winds form Himachal Pradesh, Uttarakhand and Jammu and Kashmir are the reason for the recent fall in Delhi’s temperature despite clear skies, HT reported on Tuesday. These states are experiencing heavy snowfall. The Delhi RMC has, however, forecast partly cloudy skies for the national capital from December 19 to 21, with shallow fog in the morning. This will bring relief from the cold. The skies are likely to remain clear until December 18.

November was coldest since 1949

November was exceptionally cold too in the national capital. The mean minimum temperature recorded at the Safdarjung station – considered to be representative of Delhi – was 10.2 degree Celsius. This was the lowest since 1949, when the mean minimum temperature was 10.2 degree Celsius. Four cold wave days were also experienced in the month.

December so far is warmer than 2018

To be sure, December so far has not been exceptionally cold in the national capital. The average minimum temperature observed at the Safdarjung station has been 10.15 degree Celsius. This is higher than the average minimum temperature observed during the same period in 2019 (9.05 degree Celsus) and 2018 (9.29 degree Celsius). The average maximum temperature for this period (26.7 degree Celsius) is also higher than that in 2018 (24.7 degree Celsius) and 2019 (23.1 degree Celsius) at the station.

This can change as winter progresses. The IMD considers the December to February period as winter. It had predicted below-normal minimum temperatures for most subdivisions of north and northwest India at the beginning of the season.

Minimum temperatures are rising in Delhi and neighbouring areas

The below-normal minimum temperatures and cold wave conditions this year might have to do with moderate La Nina conditions prevailing in the Pacific Ocean. La Nina refers to a weather phenomenon in the east-central Equatorial Pacific when sea surface temperatures are below the long-term average. This leads to colder winters in India. The minimum temperatures in December in both Delhi and India have, however, been rising if we look at the long-term trend.