The minimum temperature was recorded at nine degrees Celsius, an IMD official said. "The maximum temperature, however, is likely to hover around 23 degrees Celsius," the official added.
"The sky will be generally cloudy with light rains expected during the day," the official said.
At least 15 Delhi-bound trains were delayed on Monday due to fog, railway officials said.
A Western Disturbance has given rise to a cyclonic circulation over Afghanistan and Pakistan between 1.5 and 3.1 km above mean sea level, the Met said.
"Under its influence, fairly widespread to widespread precipitation with isolated heavy to very heavy falls is very likely to occur over western Himalayan region on Monday," it added.
According to the Centre-run System of Air Quality and Weather Forecasting (SAFAR), the overall air quality index (AQI) of Delhi was recorded at 356.
"The overall Delhi AQI is in the higher range of 'very poor' category on Monday morning. Under the influence of current western disturbance(WD) increased wind speed and isolated rainfall is expecting by evening.
"An improvement in AQI is likely by tonight.
"SAFAR model suggests on Tuesday, the AQI likely to further improve to the poor category and on Wednesday, a marginal deterioration in AQI and likely to stay in the upper end of the poor to the lower end of the very poor category.
"A fresh WD in quick succession is likely to influence the region by Thursday and AQI is likely to stay in better condition," SAFAR said.
( With inputs from IANS )