Environment Canada issued a Winter Weather Travel Advisory Tuesday, an unusual occurrence for mid-to-late April.
The weather agency said snowfall amounts of up to five centimetres are possible in Sarnia-Lambton Tuesday night and early Wednesday morning.
Road surfaces could become slippery and visibility could be reduced at times in falling snow.
Environment Canada said due to the uncertain track of a low pressure system moving south of the region, and warm ground temperatures, total snowfall amounts could change.
Residents are advised to monitor alerts and forecasts.