It was a clear and sunny day in the national capital on Saturday with the mercury dipping below 5 degrees. The Met forecasts overcast condition with light rain on Tuesday and Wednesday.

The air quality improved slightly from 'very poor' to 'poor' category as light breeze has been blowing since Friday.

The minimum temperature was recorded at 4.8 degrees Celcius, and the maximum was likely to hover around 21 degrees, the India Meteorological Department said.

At least 21 trains were delayed due to severe fog in several parts of northern India on Saturday, compared to 12 on Friday.

According to the Centre-run System of Air Quality and Weather Forecasting (SAFAR), the overall air quality index (AQI) of Delhi on the day was 'poor' at 208 with PM10 at 118 and PM2.5 at 63. 

SAFAR predicts further improvement in the AQI in Delhi later in the day.

"The high ventilation has helped to flush out the pollutants and led to betterment of AQI. SAFAR forecast suggest marginal deterioration in AQI during the night," said SAFAR. 

The AQI is likely to deteriorate to the poor category on Sunday.