Delhi on Thursday recorded a minimum temperature of 12.5 degree Celsius, which was the lowest in October in 26 years, PTI reported, citing data from the Indian Meteorological Department. Data from the weather department showed that the Capital had recorded a minimum temperature of 12.3 degree Celsius on October 31, 1994.

Kuldeep Srivastava, the head of IMD’s regional forecasting centre, told PTI that the absence of cloud cover caused the temperature to drop so low. The lack of clouds causes the earth’s surface to cool quickly. Srivastava added that slow winds allowed the formation of mist and fog.

The weather office said that the normal minimum temperature around this time of the year is 15 to 16 degree Celsius. It added that temperature in Delhi is likely to drop to 11 degree Celsius by November 1.

Air quality

On Thursday, Delhi’s air quality also deteriorated to the “severe” category for the first time this season. A slight improvement was recorded on Friday as the air quality level dropped to the “very poor” category, data from the Central Pollution Control Board showed.

VK Soni, head of India Meteorological Department’s environment monitoring research centre had predicted that the city’s air will improve significantly between Friday and Sunday, with wind speeds likely to touch 15 kmph on Friday, according to the Hindustan Times.

According to the Ministry of Earth Sciences’ air quality monitor, SAFAR, the share of stubble burning in Delhi’s PM2.5 concentration was 19% on Friday, according to PTI. It was 36% on Thursday – the maximum so far this season – and 18% on Wednesday. The number of farm fires in neighbouring states dropped from 2,912 on Wednesday to 1,143 on Thursday.

SAFAR also predicted a significant improvement in Delhi’s air quality by November 1. The wind speed is expected to pick up and the improved ventilation is likely to influence air quality positively, it said.

An AQI between 0 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 is considered “severe”. The index measures the concentration of pollutants finer than 2.5 microns in diameter that can reach deep into the lungs and cause diseases like cancer and cardiac problems.