A thick layer of fog shrouded Delhi on Wednesday morning, lowering visibility to 350 metres in some parts of the capital.

Senior scientist at the India Meteorological Department (IMD) R K Jenamani said this was the capital's first fog of the season.

Delhi recorded a minimum temperature of 20.2 degrees Celsius, a notch below the normal. The maximum temperature is likely to settle at around 31 degrees Celsius.

Partly cloudy weather is predicted during the day.

An official at the India Meteorological Department said the heavy mist is a result of a prolonged spell of rain, which increased moisture content in the air.

"Heavy mist reduces visibility for a small period of time but does not cause much inconvenience to commuters. It is not the season of fog yet," he said

According to the official, visibility at the Safdarjung Observatory, Delhi's primary weather station, had dropped to 600 metres and to 350 metres at the Palam weather station at 8.30 am.

This improved to 2,100 metres at Palam by 9 am and at Safdarjung by 10 am.

At 9 am, the capital's air quality index stood at 66, which falls in the "satisfactory" category.