The city, on Saturday morning, was blanketed by dense to moderate fog with lowest visibility of 300 m at Safdarjung at 7:30 a.m., while the Palam recorded 350 m at 8 a.m.

The IMD classifies fog intensity into four types -- shallow, moderate, dense and very dense fog.

The visibility ranges from 999 m to 500 m, 499 m to 200 m, 199 m to 50 m and less than 50 m, respectively.

According to Indian Railways, a total of 18 trains were running late by hours due to fog and cold waves.

The IMD had said that cold wave to severe cold wave conditions are likely over North India during the next two days while Cold day to severe day wave conditions are likely over plains of Northwest India during next three days and abate thereafter.

The IMD also predicted that dense to very dense fog conditions are likely to continue to prevail over North India during the next five days.

In its daily bulletin, the weather forecast agency said that minimum temperatures are in the range of 3-7 degrees Celsius over most parts of Punjab, Haryana, Chandigarh, Delhi, Rajasthan, in some parts of Uttar Pradesh, south Rajasthan, north Madhya Pradesh and in isolated pockets of Bihar.