When the maximum is the minimum: An explanation for Delhi's winter chill

On the intervening night of Saturday and Sunday, parts of the National Capital Region experienced cold wave conditions for the first time this winter.
 
delhi temperature

On the intervening night of Saturday and Sunday, parts of the National Capital Region experienced cold wave conditions for the first time this winter. While a wind chill factor is also considered when declaring a cold wave, the minimum temperatures in portions of Delhi on Sunday night were low — 3.3 degrees Celsius in Jafarpur and 3.6 degrees at Lodhi Road – even without it. An HT study, on the other hand, reveals that it is the maximum temperatures recorded during the day that have fallen to historical lows in December, rather than the minimum temperatures reported at night. Here are five charts that describe this trend and its underlying causes.

The average minimum temperature is the sixth-highest since 1951, however, it is declining.

The India Meteorological Department (IMD) makes historical temperature data available to the public only for grids, not individual stations or cities. These grids have a resolution of one degree: boxes with latitudes and longitudes separated by one degree. Because Delhi is too tiny to be caught by them, this research incorporates all districts surrounding Delhi in its temperature analysis. It reveals that the average minimum temperature in Delhi in December is 9.74 degrees Celsius from December 1 to December 20. It's the sixth-highest average low temperature for this time of year since 1951. This isn't due to any one day. The minimum temperature was among the top 20 highest readings for that day on 13 of the 20 days in December since 1951. However, with nearly every passing day, both the absolute lowest temperatures and the rank of 2021 for that day have decreased. This year's December 18 was the 33rd coldest on record. December 18 was the coldest December day since 1951, December 19 was the 27th coldest, and December 20 was the 11th coldest.