Ontario Provincial Police temporarily closed a section of the Highway 402 Thursday morning due to poor weather and road conditions.
The highway was closed in both directions between Nauvoo Road in Watford and Highway 401 in London.
However, the Ministry of Transportation said the westbound lanes reopened just before noon.
The eastbound lanes reopened at around 1 p.m.
Motorists are still being advised to drive slow as many roadways remain snow-covered.
School buses in Zones 1, 3, 4, and 6 were also cancelled Thursday due to inclement weather.
Buses in all other zones operated by Chatham-Kent Lambton Administrative School Services were operating normally.
A snow squall warning was still in effect for north and east Lambton.
Environment Canada said several bands of snow squalls from Lake Huron will affect the region Thursday and Thursday night.
Locally heavy snowfall with accumulations of 30 to 60 centimetres by Friday morning are possible.