Around 70 north-bound trains, including Rajdhani services, were delayed, while around 30 others were rescheduled due to fog on Thursday.
Rajdhani trains from Kolkata, Sealdah, Bhubaneswar and Patna are among the trains that were three to five hours late, a Northern Railway official said.
Departure of around 30 trains were rescheduled due to bad weather conditions, he said.
The New Delhi-Darbhanga Bihar Sampark Kranti Express, New Delhi-Gaya Mahabodhi Express, New Delhi-Jabalpur Superfast Express, New Delhi-Hyderabad Decan Telangana Express and New Delhi-Howrah Poorva Express are among the trains that were rescheduled.