In Barabanki, Manjit Kumar Verma (10) and Shivam (11) were killed this morning when their bicycle was hit by a truck at Mohammadpur crossing.
The children were on their way to school when the accident took place, police said.
In another incident in Bareilly, three people were killed and two others were injured when their SUV dashed into a tractor near Damkhora tri-section here due to fog late last night, they said today.
MeT department officials said night temperatures rose in Bareilly and fell appreciably in Kanpur and in Allahabad while it changed marginally elsewhere.
"Night temperatures were appreciably above normal in Jhansi while being normal in the remaining divisions of the state," they said, adding minimum temperature was recorded in Najibabad at 8.5 degree Celsius.
The MeT forecast says weather will most likely remain dry and shallow to moderate fog is very likely to occur in the morning at isolated places of the state.