The mercury dipped to a minimum temperature of 5.7 degrees Celsius, while it shot up to touch a maximum of 20 degrees Celsius, both a notch below the season's normal, the weather department said.
The humidity levels oscillated between 100 and 57 per cent, a MeT official said.
According to Railway's official data, as of December 31 midnight, 400 mail and express trains reached their destination late after getting delayed on account of fog.
As of today, 6:30 am, 56 trains arrived late, 20 were rescheduled and 15 trains were cancelled.
Over 300 flights were also delayed and eight cancelled as dense fog severely hampered visibility at the Indira Gandhi International airport here.
The weatherman has predicted similar conditions for tomorrow with a possibility of dense fog in the morning and early evening hours.
Yesterday, the minimum temperature had settled at 6.4 degrees Celsius, a notch below normal.