Environment Canada is tracking thunderstorms from Michigan that are expected to strengthen as they move into Ontario Friday night.
A severe thunderstorm watch has been posted for Sarnia-Lambton, Chatham-Kent, and Windsor-Essex.
Heavy downpours, strong winds and large hail are possible.
The agency warned that downpours can cause flash floods and water pooling on roads, hail can damage property and cause injuries and strong wind gusts can toss loose objects, damage weak buildings, break branches off trees and overturn large vehicles.
Emergency Management Ontario recommends that you take cover immediately if threatening weather approaches.
