New Delhi, Jan 14 (IANS): The fog was back in the national capital Monday with Delhiites waking up to a grey morning after a few days of clear sunshine. Low visibility hampered movement of air, rail and road traffic.

The city woke to a dense fog. At 8.30 a.m., visibility was reduced to 50 metres, and road traffic slowed to a crawl.

Monday's minimum temperature settled three notches above average at 10.6 degrees Celsius. The maximum is expected to hover around 22 degrees Celsius, an India Meteorological Department (IMD) official said.

A railway official said 10 trains were cancelled and 20 delayed by the fog.

"Over 20 trains were running behind schedule by several hours and 10 trains have been cancelled. Dense fog across many parts of north India today (Monday) affected rail services," a Northern Railway spokesperson said.

The fog also disrupted operations at the Indira Gandhi International airport Monday morning.

"About 20 flights have been delayed, among them two international flights and eight domestic ones. Nine domestic flights were diverted, as visibility dropped to 50 metres," an official of the Delhi International Airport Limited (DIAL) said.

An IMD official, however, held out hope for clear skies.

Motorists who had to set out early Monday, especially those who left homes in National Capital Region (NCR) areas like Noida and Gurgaon to drive into Delhi were hit hard, as the fog was dense and visibility poor.

"Nothing but the fog was visible, how could I drive," said Sanjeev Mishra, who commutes from Noida to Delhi for work.

Sunday's maximum and minimum temperatures were both two notches above average for this time of year at 22.9 degrees Celsius and 9.4 degrees Celsius respectively.

The Met department said the coldest day of the season so far was Jan 6, when the minimum temperature dropped to 1.9 degrees.