Dense to very dense fog observed at isolated places over Punjab, Haryana and the Gangetic West Bengal on Thursday early morning.
According to Indian Meteorological Department (IMD), a moderate fog was observed at isolated places over South-West Uttar Pradesh, sub-Himalayan West Bengal and Sikkim at 5:30 am.
The national capital was also enveloped in fog early this morning and according to Northern Railways, as many as 20 trains were running late due to poor visibility.
For the past several days, rail operations have been hit by primarily dense fog.