New Delhi, Feb 11 (IANS): It was a cold Monday morning in Delhi as the minimum temperature was recorded at 7 degrees Celsius, three notches below the season's average, while the overall air quality deteriorated to the "poor" category, the weather office said.

"There was shallow to moderate fog in the morning. Clouds will partly cover the skies on Monday with a forecast of haze or smoke engulfing the city later in the day," an India Meteorological Department (IMD) official said.

Due to fog, at least 15 Delhi-bound trains were delayed by three to four hours with one - Nizamuddin Express - running late by six hours.

The maximum on Monday is expected to reach 21 degrees Celsius, which is two notches below the normal.

The overall air quality levels in the city at 9 a.m. was recorded at 259 ("poor") after days of improved "moderate" air.

However, the System of Air Quality and Weather Forecasting And Research (SAFAR) has forecast that the air quality will improve if the predicted rain occurs on Thursday.

The humidity at 8.30 a.m. was recorded at 95 per cent -- an unfavourable condition for the pollutants to disperse.

Sunday's maximum temperature was recorded at 21.6 degrees Celsius, a notch below the season's average and the minimum temperature was recorded at 6 degrees Celsius, three notches below the normal.