New Delhi, Dec 16 (IANS): The India Meteorological Department (IMD) has forecast a partly cloudy sky with very light rain or drizzle likely towards the evening or night on Thursday, with the maximum and minimum temperatures dropping to 22 degrees Celsius and 9 degrees, respectively.

On December 19, the maximum temperature is likely to dip to 21 degrees Celsius and for the next day, the minimum temperature has been pegged at 5 degrees as a result of a coldwave that will hit the isolated pockets over Punjab, Haryana, Rajasthan from December 18 to 20.

The relative humidity at 8.30 a.m. was recorded at 90 per cent.

Meanwhile, Delhi's air quality settled under the 'very poor' category with the System of Air Quality and Weather Forecasting And Research's (SAFAR) recording the Air Quality Index (AQI) at 337 at 9.30 a.m.

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'; 401 and 500 'severe'.

The level of PM10 and PM2.5 pollutants in the air was recorded in the poor and very poor category at 9.30 a.m.

"The air quality is likely to improve further and remain in the lower end of 'very poor' to 'poor' category on December 16 and 'poor' category on December 17. The air quality is likely to improve significantly and remain in the 'poor' to 'moderate' category," the air quality and weather bulletin said.