The minimum temperature in Delhi on Tuesday went down to 10 degrees Celsius – the season’s lowest so far, the India Meteorological Department said, according to PTI. A cold wave may be declared in the Capital if the situation persists for one more day, the weather department added.

The Capital’s minimum temperature was less than Dalhousie, which recorded 10.9 degrees Celsius, Dharamshala (10.6), and Mussoorie (10.4). Shimla in Himachal Pradesh and Nainital in Uttarakhand also registered their lowest temperatures at 10 degrees Celsius.

“The trend of below normal minimum temperature continues,” said Kuldeep Srivastava, the weather department’s head of the regional forecasting center. “A similar situation is expected to prevail for another four to five days.” For the plains, the met department declares a cold wave when the minimum temperature is 10 degrees Celsius or below, and 4.5 notches below normal for two straight days.

Srivastava said that November is likely to be the coldest in the past four to five years. The Safdarjung Observatory, which collects data for the city, records a minimum of 14.8 degrees Celsius in the first week of November. Eleven to twelve degrees Celsius is recorded by the last week of the month, a weather department official said.

The mercury may dip to single digits in the next three to four days, the weather department official said.

Meanwhile, the Capital’s air quality dropped to the very poor category again on Tuesday after a marginal improvement over 24 hours. The India Meteorological Department said the air quality had improved on Monday due to high wind speed facilitating dispersion of air pollutants. However, stagnant night-time weather conditions led to accumulation of pollutants, reported PTI.

On Tuesday, at 1 pm, Delhi’s air quality was recorded at 336 in the “very poor” category, according to the Central Pollution Control Board. According to SAFAR, the overall AQI was recorded at 316. An AQI between 0 and 50 is considered “good”, 51-100 falls under “satisfactory” zone, 101-200 is “moderate”, 201-300 “poor”, 301-400 “very poor” and 401-500 is “severe” category. A fall in temperatures makes the air cold and heavy, leading to accumulation of pollutants near the ground.

The contribution of stubble burning in Delhi’s air pollution levels reached 40% on Sunday, the highest so far in this season. “Air quality may deteriorate to a severe category in Delhi if wind speed reduces,” India Meteorological Department’s air quality division scientist Vijay Soni had said.

The wind speed on Tuesday is likely to remain between five and 12 kmph, the weather department said, according to Hindustan Times.