The average minimum temperature this November in Delhi reached 10.2 degrees Celsius — a mark previously recorded 71 years ago in November 1949 — data from the India Meteorological Department (IMD) shows.
Cold winds blowing from northern regions of the country and clear skies were credited as the two main reasons for the drop in mercury. The last time average minimum or night time temperature dropped below 10.2 degrees Celsius in Delhi in November was in 1938, when it was 9.6 degrees Celsius, IMD data shows.
However, IMD scientists also said the La Niña weather phenomenon, which is currently active, has been influencing temperatures.
La Niña refers to the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall, as per the World Meteorological Organisation (WMO), a United Nations agency.
Kuldeep Srivastava, head of IMD’s regional weather forecasting centre in Delhi, said, “La Niña has an impact on temperatures across the globe. When this phenomenon is active, there is a possibility that winter temperatures would remain lower than usual.”
Srivastava said significant amount of snowfall has been recorded in high altitude areas of Himachal Pradesh, Jammu & Kashmir and Uttarakhand since mid-November, which was also connected with La Niña.
“Cold northwesterly winds blowing over Delhi from these areas caused minimum temperatures to drop to below normal levels on most days this month. Additionally, the sky over the city remained largely cloudless, which led to higher radiation from the earth at night time and more cooling,” he said.
Delhi witnessed 0.6 mm of rainfall on November 16, which, along with cloud cover, helped minimum temperature to rise up to 16 degrees Celsius.
However, after November 16, with clearing of cloud cover, minimum temperature began dropping rapidly, reaching up to 6.3 degrees Celsius on November 23 — lowest for the month since November 29, 2003, when it was 6.1 degrees.
Four cold wave days were also recorded this November. Among previous years since 2011, only November 2014 and 2013 have recorded cold wave days — one each.
As of Monday, minimum temperature at the IMD’s Safdarjung observatory, which is representative of Delhi, continued to drop and was recorded at 6.9 degrees Celsius.
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