The cold wave is likely to return to Delhi-NCR next week with the minimum temperature expected to settle around 3 degrees Celsius, the India Meteorological Department said.
The minimum temperature in the national capital on Saturday settled at 10.2 degrees Celsius, three notches above the season's average, it said.
The maximum temperature was recorded at 18.4 degrees Celsius, two notches below the season's average, while the humidity oscillated between 88 per cent and 57 per cent.
The weather office has predicted shallow fog for Sunday with the maximum and minimum temperatures likely to settle around 17 and 7 degrees Celsius, respectively.
The Met office has predicted a cold wave to prevail over many places in Delhi-NCR between Monday and Wednesday. The minimum temperature at Ayanagar and Ridge may settle around 3 degrees Celsius on Tuesday and Wednesday.
Large parts of north and northwest India recorded below-normal maximum and minimum temperatures on most days this month before a western disturbance brought relief, an IMD official said. This was due to a layer of dense fog persisting over the Indo-Gangetic plains for the past 10 to 11 days and a large gap between two western disturbances that allowed frosty winds from snow-clad mountains to blow in for a longer-than-usual period, he added.
The Indo-Gangetic plains have a lot of moisture owing to the large number of water bodies and rivers in the region. High moisture content, low temperatures and calm winds are the recipe for dense fog, the official explained.
"The region recorded below-normal maximum temperatures this month so far due to dense fog, which reduced sunshine hours. Low day temperatures mean early cooling and early fog formation in the evening," he added.
Once the prevailing western disturbance retreats, frosty northwesterly winds will start blowing towards the plains.
In the plains, a cold wave is declared if the minimum temperature dips to 4 degrees Celsius or when it is 10 degrees and 4.5 notches below normal.
A severe cold wave is when the minimum temperature dips to 2 degrees Celsius or the departure from the normal limits is by more than 6.4 notches. A cold day is when the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 notches below normal.
A severe cold day is when the maximum temperature is at least 6.5 notches below normal. According to data from the Central Pollution Control Board, the overall Air Quality Index (AQI) at 7 pm was 'very poor' at 340.
An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
-With PTI Input
