New Delhi, Dec 9 (IANS): The minimum temperature in Delhi is likely to dip to 7 degrees Celsius on December 12 and 13, as per India Meteorological Department (IMD) forecast.

On Thursday, Delhi woke up to its minimum temperature settling at 9 degrees Celsius, and shallow fog. The air quality was at the lower end of the 'poor' category at an AQI of 208.

The level of PM 2.5 and PM 10 at 9 a.m. stood in the poor and moderate categories.

An Air Quality Index (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', then 401 and between 500 is considered 'severe'.

System of Air Quality and Weather Forecasting And Research's (SAFAR) Wednesday summary read, "For the next four days, i.e., December 8 to December 11, winds are likely to be moderate, increasing ventilation of pollutants. Minimum temperatures are likely to drop gradually leading to a more stable boundary layer during nighttime that helps accumulation of pollutants.

"With mostly clear sky conditions during the daytime, the peak mixing layer height is likely to be around 1.5 km causing moderate vertical mixing of the air mass. The net effect is that air quality for the next four days is likely to improve gradually but within the 'Moderate' or 'lower end of Poor' category," it added.

Meanwhile, the maximum temperature for the day has been pegged at 24 degrees Celsius.

The relative humidity at 8.30 a.m. stood at 92 per cent.