Delhi's minimum temperature dropped to 4.2 degrees Celsius, three notches below normal, on Friday even as foggy conditions disrupted traffic movement, the India Meteorological Department (IMD) said.

Moderate fog lowered visibility to 350 metres at Safdarjung and Palam, officials said.

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

A fresh Western Disturbance affecting the western Himalayas is likely to provide some relief from the chill. The minimum temperature is expected to increase to 9 degrees Celsius by Sunday as a result of easterly winds and cloud cover.

Easterly winds have already started blowing in the national capital. A cloud cover will further increase the minimum temperature on Saturday and Sunday," Kuldeep Srivastava, the head of the IMD's regional forecasting centre, said.

Easterly winds are not as cold as northwesterly coming in from the snow-clad western Himalayas, while clouds trap some of the outgoing infrared radiation, increasing the minimum temperature.

However, Srivastava said, the minimum temperature will again drop to four degrees Celsius by Monday.

The WD will lead to widespread snowfall in the upper hills of Jammu and Kashmir, Himachal Pradesh and Uttarakhand. Cold, dry winds from the snow-capped mountains will bring the mercury down to 4 degrees Celsius by Monday, he said.