The maximum temperature is expected to hover around 23 degrees Celsius.
Moderate to dense fog occurred at several places in the city. Visibility dropped to 100 metres at Safdarjung observatory, the department said.
Weather experts had earlier said there would be no cold wave until January 8.
Light rains are expected in the capital anytime between January 6 and 8 due to a fresh western disturbance.
Widespread rains may also help reduce pollution levels. The overall air quality index stood at 300 (very unhealthy) at 9 am.