The air quality of the national capital deteriorated on Thursday and settled in the severe category with the AQI clocking at 419 at 8 am, even as the minimum temperature settled four notches above the season's average at 13.4 degrees Celsius.

According to Ministry of Earth Science's air quality monitor SAFAR', the air quality is likely to improve from Friday onwards due to better wind speed.

From December 3 onwards, winds are expected to increase dispersing pollutants but the AQI is likely to remain in the 'very poor' category. Low mixing layer height is preventing efficient dispersion of pollutants, SAFAR said in its advisory.

On Wednesday the city's 24-hour average Air Quality Index (AQI) read 370. It was 328 on Tuesday.

Neighbouring NCR towns Faridabad (441) and Noida (404) also witnessed severe air quality on Thursday morning. However, the AQI in Ghaziabad (359), Greater Noida (381), Gurugram (361) was in the very poor category.

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".

Meanwhile, the weather office has forecast light rain on Thursday.

There will partly cloudy sky with light rain or drizzle in the city on Thursday, the India Meteorological Department (IMD) said.

The weather office said maximum temperature is likely to hover around 22 degrees Celsius.

The relative humidity at 8.30 am was 81 per cent, it said.