The A418 between Wing and Aylesbury was closed on Sunday evening due to flooding.
Transport for Buckinghamshire were called on Sunday night to the A418, just south of Wing, where a car had gone off the road following impact with standing water on the southbound carriageway.
The road was closed and messages were sent out asking drivers to plan ahead and avoid the area if possible.
A spokesperson for Buckinghamshire County Council, said: “After discussion with the police the road was closed southbound.
“Traffic signals were then installed in order to reopen the road in time for Monday morning, but traffic was very heavy through the morning rush hour and is affecting surrounding areas.
“The signals remained in place until the water levels dropped and were removed by 11am, Monday morning.”