The IMD said there will be shallow to moderate fog over the city for the next two days.
Delhi witnessed the lowest maximum temperature of the season so far on Thursday as it plummeted five notches below normal and settled at 19.8 degrees Celsius even as the weather office predicted foggy days ahead.
Several areas of the city also witnessed light rains or drizzle on Thursday, the weather office said.
Senior scientist at the India Meteorological Department (IMD) RK Jenamani told PTI, "The maximum temperature settled at 19.8 degrees Celsius, five notches below normal. It is the season's lowest maximum temperature so far. More colder days are ahead."
He added that it was not a cold day as the second condition of any cold day over a station in the plains is that its minimum temperature needs to be less than 10 degrees Celsius.
The minimum temperature in Delhi was recorded at 13.4 degrees Celsius, four notches above the season's average.
The IMD said there will be shallow to moderate fog over the city for the next two days.
Mr Jenamani said as predicted, Delhi witnessed poor visibility throughout the day with very light rainfall in the afternoon.
"Palam IGI airport has reported visibility of 700-800 metre in shallow fog/smog till 10 am and then improved to 1200 metre till 1 pm. Thereafter, it was 500-800 metre in mist/light rainfall till evening. Winds were calm in most parts of the day with some 5-10 kmph for some times in the afternoon," he said.
He added that at Safdarjung airport, the visibility was consistently poor with 600-800 metre in mist or smog in the first half and then drizzle and mist between 1.30 pm and 6.30 pm.
The weather office said the minimum and maximum temperatures are likely to hover around 12 degrees Celsius and 22 degrees Celsius respectively on Friday.
The relative humidity oscillated between 81 per cent and 94 per cent, the IMD said.