After staying in the 'severe' category for six days, Delhi's air quality improved to the 'poor' category on Monday following rains a day before, while the maximum temperature settled at 22.6 degrees Celsius, two notches above the season's average.

The 24-hour air quality index (AQI) of Delhi read 283 at 4 pm. The AQIs of its neighbouring cities -- Faridabad (260), Ghaziabad (212), Gurugram (250), Greater Noida (242) and Noida (226) -- were also recorded in the 'poor' category.

The government's air quality forecast agency SAFAR said that the AQI improved on Monday "due to last night rain that scavenged particulate matter through wet deposition".                On Tuesday, winds are likely to be low, reducing ventilation of pollutants, with the AQI expected to be 'very poor', the System of Air Quality and Weather Forecasting and Research (SAFAR) said.

"On 29th (Wednesday) improvement is expected due to high easterly winds that enhances ventilation of pollutants. Mixing layer height continues to be low (less than 1.0 km) and minimum temperature tends to drop gradually. The net effect is that AQI remains to be within 'very poor' till 31st (December) and from 1st (January) onwards it is likely to improve to 'poor'," it said.

The AQI was recorded in the 'severe' category on Sunday evening at 459, according to Central Pollution Control Board (CPCB) data. On Monday morning, it was 373.    The city's 24-hour average AQI read 431 at 4 pm on Saturday. It was 415 on Friday, 423 on Thursday, 407 on Wednesday and 402 on Tuesday.             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'.   The city has recorded 23 'severe' air quality days in this year so far. In November, it recorded 11 such days, the highest in the month since the CPCB started maintaining air quality data in 2015.