New Delhi: Delhi recorded a “cold day” on Sunday, as the maximum temperature dropped to 15 degrees Celsius, six notches below normal and the lowest this month, the India Meteorological Department (IMD) said. Also Read - Lakshadweep: Amid Adverse Weather, 7 Crew Members of Sunken Ship Rescued in Daring Air-Sea Operation

A “cold day” is when the minimum temperature is less than 10 degrees Celsius and the maximum is at least 4.5 degrees Celsius below the normal. Also Read - Thick Fog, Windy Weather Predicted For Delhi in Coming Days; Snowfall Forecast in Hills

The minimum temperature settled at 8.8 degrees Celsius. However, it is expected to drop by three to four degrees Celsius over the next three days, leading to “cold wave” conditions, the IMD said. Also Read - Cold Wave Returns to North India, Delhi's Minimum Temperature Drops to 7 Degrees Celsius

“A cold wave is likely to grip the city on Tuesday. Dense to very dense fog is also predicted,” Kuldeep Srivastva, the head of the IMD’s regional forecasting centre, said.

In the plains, the IMD declares a cold wave if the minimum temperature dips to 4 degrees Celsius. A severe cold wave is when the minimum is 2 degrees Celsius or less.

Earlier in the day, “dense” fog reduced visibility to 200 metres at Safdarjung and 100 metres at Palam.

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.