The base observatory Safdarjung recorded minimum temperature 3.3°C today, lowest of this season and 4°C below the normal. Consequently, 31st December is the 3rd consecutive cold wave day for Delhi recording minimum temperature of 3.6°, 3.5° and 3.3°C on 29th, 30th and 31 December 2020 respectively. Incidentally, the last day of 2020 goes on record to be the coldest of this season overtaking the previous low of 3.4°C on 20th December 2020. The mercury plummeted to 3.1°C at Lodhi Road today measuring lowest in Delhi area.
Today 31st December was the 8th cold wave day recorded this month and takes distinction of being the highest in the last 28 years. Of course, it shares this feat and equals the highest number of 8 cold days last counted in 2018. A cold wave day is declared when the minimum temperature is 4°C or more below the normal or the minimum temperature is less than 4°C. Last 3 days of December 2020 have been meeting both the criteria and thereby setting a record in recent history.
December 2019 was a shade colder than 2020 when the lowest minimum of 2.4°C recorded on 28th. Prior to this 29th December 2018 recorded the lowest minimum temperature of 2.6°C. December 2019 was the 2nd coldest in Delhi since 1901 and it recorded the mean maximum temperature (MMT) of 19.15°C against the monthly normal of 23.1°C. In the year 1997, December remains the coldest on record so far when the MMT got settled at 17.3°C. Since 1901, there are 5 years (1919, 1929, 1961, 1997, and 2019) when the month of December registered a mean maximum temperature of less than 20°C (<20°C). December 2020 observed 2 warm spells when the daily maximum was more than the normal. The first 11 days of the month recorded temperature between 26- 29°C and again between 21st and 28th December, the range varied between 22-24°C. The overall mean maximum temperature for December 2020 is likely to be at 23°C, very close to its normal of 23.1°C. However, nights have been relatively much colder with minimum temperature less than 5°C on 12 days.
Relief is expected from extreme cold conditions as the minimum temperature is likely to rise to 7-9°C between 02nd and 06th January 2021. Rain and thundershower are expected on these days possibly accompanied with hailstorm on 4th and 5th January. The normal rainfall of 19.3mm in January is likely to be achieved during the 1st week of January 2021.