Day temperatures remained near normal over many parts of Northwest India until December 20. The sky was clear and the day remained sunny. Moderate winds were overblowing across Northwest India, which did not allow the formation of dense fog. Wind speed dropped significantly across Indo-Gangetic plains and moisture content also increased in lower tropospheric levels leading to the formation of dense fog.
Fog persisted throughout the day over many parts of Punjab, Haryana and North Rajasthan and did not allow the temperatures to rise much. Cold day conditions were observed over many parts of Punjab. Maximum temperature of Amritsar was just 11.8 degrees. Similarly, Ganganagar in another Rajasthan recorded 13 degrees. Maximus of Ludhiana, Patiala, Hisar and Karnal remained between 14 and 16 degrees.
Maximum temperature of Delhi and NCR also dropped below 20 degrees. Cold day is declared when minimum temperature is below 10 degree and maximum is at least 4.5 degree below normal. No wind speed is expected to increase from Northwest which may thin down the density of fog and temperatures may increase marginally leading to abatement of cold day from some parts.