Delhi witnessed dense fog in parts of the city on Saturday, with the minimum temperature settling at 10.2 degrees Celsius, three notches above the season's average, the India Meteorological Department said.

Relative humidity recorded at 8:30 am was 90 per cent, it said.

The maximum temperature is likely to hover around 21 degrees Celsius in the national capital.

The India Meteorological Department (IMD) has predicted partly cloudy skies during the day with dense fog in the morning.

Visibility at Palam dropped down to 250 m for a short span of time during 1 am to 2 am and improved again becoming 800 m at 6 am. Visibility was less than 200 m at 5:30 am over Bhatinda, Chandigarh-50 m, Ambala-25 m, Bareilly-25 m, Lucknow-25 m, Varanasi-50 m, Patna-25 m, and Gaya-50 m, according to IMD. Delhi's minimum temperature rose to double digits for the first time in 15 days on Friday, but the respite is predicted to end soon.

The IMD said icy winds from the Himalayas will bring the minimum temperature down by three to five degrees Celsius in the plains of northwest India. "Dense fog is likely to continue over the region during the next four to five days. A fresh cold wave spell is likely to commence over northwest India from January 1," it said in a statement.

The Safdarjung observatory, the city's primary weather station, on Saturday recorded a minimum temperature of 10.7 degrees Celsius, four notches above normal. It was also the highest minimum temperature this month.

With the western disturbance retreating by Saturday, cold wave and cold day conditions are predicted to wallop parts of Delhi in early January, meteorologists said.

The mercury will drop to 8 degrees Celsius on Saturday and further to 4 degrees Celsius by January 2. Dense fog and cold wave conditions are predicted in parts of Delhi from January 1 to 5, according to the meteorological department.

A cold day is when the minimum temperature is less than or equal to 10 degrees Celsius below normal and the maximum temperature is at least 4.5 degrees Celsius below normal. A severe cold day is when the maximum is 6.5 degrees Celsius or more below the normal.

According to IMD, ''very dense'' fog is when visibility is between 0 and 50 metres, 51 and 200 metres is ''dense'', 201 and 500 metres ''moderate'', and 501 and 1,000 metres ''shallow''.

In the plains, the meteorological office declares a cold wave if the minimum temperature dips to 4 degrees Celsius or when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches below the normal.

A severe cold wave is when the minimum temperature dips to 2 degrees Celsius or the departure from the normal is more than 6.4 degrees Celsius.

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