Delhi witnessed a foggy morning Thursday with the visibility dropping to 400 metres as the city recorded a minimum temperature of 9.8 degrees Celsius, three notches above the season's average.

According to the meteorological department, moderate fog was witnessed at Safdarjung observatory, considered the official marker for the city, and visibility here was 400 metre.

Dense fog conditions prevailed at Palam observatory where visibility dropped to 50 metres Thursday morning.

Meanwhile, foggy conditions led to delay in arrival of around a dozen Delhi-bound trains, railway officials said.

The city will witness moderate fog on Thursday. The maximum temperature of the day will hover at around 19 degrees Celsius, the India Meteorological Department (IMD) said.

The maximum temperature on Wednesday had settled at 18.1 degrees, two notches below the normal.

The relative humidity at 8.30 am on Thursday was 95 per cent, the weather office said.

Delhi's air quality was also recorded in very poor category on Thursday as the AQI value at 8 am was 368, the Central Pollution Control Board (CPCB) data showed.

The AQIs of its neighbouring cities -- Ghaziabad (366), Gurugram (318), Greater Noida (333) and Noida (345) were also recorded in the very poor category.

Air quality in Faridabad was in a severe category with AQI at 8 am recorded at 416.

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.