New Delhi, Jan 31 (IANS): Delhi's air quality took a sudden downward turn on Wednesday to 'very poor' after days of improved 'poor' to 'moderate' category. Experts, however, say rain forecast from Wednesday night might bring down pollutants in the air.

"Overall air quality deteriorated over Delhi to very poor category as expected. This deterioration is a typical pre-shower winter impact. Now winds have also declined a bit. However, there is likelihood of rain tomorrow, which may bring the AQI into moderate category," System of Air Quality and Weather Forecasting and Research (SAFAR) said.

However, the agency said if there is no rain, the air quality will deteriorate further into the very poor zone for the next two days.

The overall air quality index (AQI) of Delhi on Wednesday was recorded at 327 (very poor), against Tuesday's 'poor' yet better AQI of 276.

In the national capital region, Ghaziabad, Greater Noida and Noida also dropped to the very poor zone with AQI above 300. Faridabad and Gurugram, however, maintained their poor air quality.

The India Meteorological Department (IMD) has forecast light rains accompanied by hailstorm from Wednesday night till February 1 which could help bring down pollutants.

Due to clouds covering the sky, the minimum temperature over the national capital will also rise by 2-3 degrees Celsius.

"From Thursday, the minimum temperature might hover around 7-8 degrees Celsius, while the maximum is expected to be around 19-21 degrees Celsius," the IMD said in its forecast.

On Wednesday, the minimum temperature in Delhi was recorded at 5.2 degrees Celsius and the maximum was recorded at 20.9.

From February 2-4, rain is again likely to subside and shallow to moderate fog might engluf the city during morning hours.