The minimum temperature in Delhi on Tuesday morning dipped to 4.1 degrees Celsius, the lowest in the national Capital so far this season, PTI reported, citing the India Meteorological Department. The temperature, recorded at Safdarjung Observatory, was five degrees below normal.

“We are recording cold wave conditions in Delhi with minimum temperature falling over 4.5 degrees below normal at many stations,” said Kuldeep Shrivastava, head of regional weather forecasting centre, according to the Hindustan Times. Cold wave sets in when the minimum temperature dips 10 below degrees Celsius and is 4.5 degrees less than the normal for two consecutive days.

“However, for small areas such as Delhi, a cold wave can be declared if the criteria is fulfilled even for a day,” Srivastava said. The temperature at Jafarpur was recorded at 3.6 degrees Celsius. It was 4 degrees Celsius at Aya Nagar weather station. The temperatures recorded at Safdarjung provide representative data for the entire city.

In its forecast, the weather agency said that cold conditions or severe cold conditions were likely in pockets of Delhi, Punjab and Haryana during the next 48 hours. It also said that most parts of north India could witness a fall of three to five degrees Celsius in minimum temperature during the next three days.

“What we are seeing now is that several parts of northwest India are experiencing severe cold day conditions,” Srivastava said. “While cold day conditions are associated with overcast sky which hasn’t allowed the day temperature to rise, even night temperatures are falling.”

He added that an intense western disturbance has passed and winds have changed to north-westerly direction, bringing icy cold winds to the plains. The cold winds had led to the decline in the maximum temperature in the city on Monday to 19.4 degrees Celsius, four degrees below normal and also the lowest so far in December.

Meanwhile, the air quality index in Delhi was in the “moderate” category at 197 at 11 am, the Central Pollution Control Board data showed. In the National Capital Range, the AQI in Gurugram’s Sector 51 was 106, while it was 208 in Noida’s Sector 62 at 11 am.

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”.