New Delhi, Dec 24 (IANS): There was fog in Delhi early Tuesday, but visibility improved as the day progressed. Four trains were cancelled and three flights were diverted, said authorities.

"Due to the fog, there has been cancellation of four trains going from Delhi and delay of 52 trains en-route to Delhi," said Northern Railway spokesperson A.S. Negi.

Five trains were rescheduled, the spokesperson said.

However, no flights were cancelled due to the fog, even though the visibility remained low on the runways.

"Early in the morning, the visibility was below 50 metres... So three flights have been diverted. Now that the fog is starting to clear, all the runways are operational," said Kapil Sabarwal, spokesperson of the Indira Gandhi International Airport.

According to the India Meteorological Department (IMD), the visibility at 8.30 a.m. was 400 metres.

The Met Office has forecast a clear day ahead with the minimum temperature recorded a notch above the season's average at 8.5 degrees Celsius.

Humidity at 8.30 a.m. was 100 percent.

The day's maximum temperature is likely to hover around 19 degrees Celsius.

Monday's minimum temperature was recorded five notches above the season's average at 12.5 degrees Celsius, while maximum was 18.4, three notches below the season's average.