New Delhi, Jan 13 (IANS): A blanket of thick fog engulfed the national capital Tuesday. Over 40 trains were delayed as the visibility dropped to 50 metres at 8.30 a.m. However, flights remained unaffected, officials said.

According to the Northern Railway, around 40 trains coming to the city were delayed while the departure time of four trains was rescheduled. Eight trains were cancelled.

The fog also affected city traffic as vehicles had to crawl and snarls were reported from some of the major intersections of the city.

However, officials at the Indira Gandhi International Airport here said that no flights were affected by the fog.

"There is no impact on operations (of flights) due to Delhi weather," an official told IANS.

The Met Office here has forecast a clear afternoon with partly cloudy sky, and added fog is likely to return in the evening.

"The afternoon will be clear and the sky will remain partly cloudy. Fog is likely to return in the evening," said an official of the India Meteorological Department.

The maximum temperature is likely to hover around 16 degrees Celsius.

Tuesday's minimum temperature settled four notches below the season's average at 4 degrees Celsius, while the humidity at 8.30 a.m. was 100 percent.

Monday's maximum temperature was 16.2 degrees Celsius, five notches below the season's average while the minimum settled at 5.7 degrees Celsius, two notches below the season's average.