Yes, you heard it right, the blue skies that have been a complete treat for the Delhi-NCR over the last two months, off and on, are set to get grey.

The forecast of the "very poor" air quality is predicted mainly due to changing local weather conditions.

According to pollution watch by Safar (System of Air Quality and Weather Forecasting and Research) India, developed by Ministry of Earth Science and Indian Institute of Tropical Meteorology, Pune the overall air quality of Delhi is in the higher end of the poor category.

"Further deterioration of the AQI is expected by October 15 to very poor category," it said.

The stubble burning activity in Haryana, Panjab, and nearby border regions are moderate but increasing. Safar said it is not necessarily affecting Delhi air if distance weather conditions establishing transport pathways are not favourable.

In the present scenario, although the magnitude of biomass-related transport is not very high but upper winds are flowing from North-North West towards Delhi with good speed and hence favourable enough to influence Delhi AQI with a share of more than 8 per cent by tomorrow (Tuesday) as per SAFAR forecasting model.

After the monsoon withdrawal, the surface wind speed in Delhi continues to be slow and variable with predominant direction from the Northwest.

The pollution causing score of PM 2.5 was at 114 in the poor category while PM 10 was at 208 in the moderate category.