A thick layer of fog continued to envelop the national Capital on Tuesday, a day after the city witnessed the season’s first episode of fog, said officials of the India Meteorological Department (IMD). There was moderate fog at Palam with visibility of 300 metres this morning.

The fog spell also added to the foul air quality, with the air quality index at 7am being 394, in the very poor category, according to the Central Pollution Control Board.

IMD forecast for Tuesday read that dense fog in isolated pockets was expected over Punjab, Uttar Pradesh, Haryana, Chandigarh, Delhi, Uttarakhand, Odisha, West Bengal, Bihar, Manipur, Mizoram,Tripura and Assam and Meghalaya. Isolated heavy rain and snow was also expected over Jammu and Kashmir, Ladakh, Gilgit-Baltistan, Muzaffarabad today.

On Monday, at the Safdarjung Observatory — representative of Delhi’s weather, moderate fog was observed with the visibility reduced to 300 metres at 8.30am.

“The season of fog has started. Easterly winds that were blowing over Delhi till Sunday noon brought moisture. High moisture content combined with low wind speed resulted in heavy fog. On Tuesday, we are expecting dense fog at Safdarjung while very dense fog at Palam,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre.

He added that at Safdarjung, the visibility may reduce to less than 200 metres on Tuesday morning. Also, air quality is likely to remain in the higher end of very poor because of the impact of fog, which makes the air heavier, allowing higher concentration of pollutants. “Though moisture content will start reducing from Tuesday, its impact will be felt only later in the day. Also, wind speed will pick up to 10-12 kmph, which may result in an improvement in air quality on December 9-10,” said Srivastava.

Also, Delhi may see very light rain or drizzle on December 11 on account of a Western Disturbance that will affect the whole of northwest India. “Till at least December 12, there will be no significant change in the morning and night temperatures. Only after the passing of the WD, there could be a drop in temperature,” he said.

On Monday, the minimum temperature was 12 degrees C, three notches above normal. The maximum settled at 26.3 degrees C, two notches above normal.