Environment Canada says patchy frost is expected tonight in Chatham-Kent and Rondeau Park.
Temperatures are expected to fall to near the freezing mark for areas inland from the Great Lakes. Light to moderate southwesterly winds overnight may prevent frost from forming in some areas.
The weather agency says damage to plants, trees and crops is possible, and it is urging people to take preventative measures to protect cold-sensitive vegetation.
Residents are asked to continue monitoring alerts and forecasts from Environment Canada. Severe weather can be reported by email to ONstorm@ec.gc.ca or on social media using #ONStorm.
