Durham Regional Police Service (DRSP) last night said the heavy rain was causing issues with traffic lights, even as utility companies put their restoration crews on alert.
If lights are not working properly treat the intersection as an all-way stop, said a tweet from DRPS Central East Division.
The best course of action right now is to stay home and stay dry, it added.
Meanwhile, Elexicon Energy was ready for emergencies.
“We are tracking a band of severe thunderstorms in our service area. Our power restoration team is on alert. If you spot an issue please call our outage hotline 1-866-579-6819. Stay safe!”
Once the storm passed Elexicon said its crews were working to assess and restore power to several areas affected during the storm.
Environment Canada yesterday evening put Durham Region under a severe thunderstorm watch.
At 10:08 pm (EDT), Environment Canada meteorologists were tracking a severe thunderstorm capable of producing strong wind gusts, pea to dime size hail and heavy rain.
This line of severe thunderstorms was located from Brampton to North York to Newcastle, moving southeast at 35 kmh.
Environment Canada forecast rain of 50 to 75 mm and wind gusts of up to 70 kmh.
It said heavy downpours can cause flash floods and water pooling on roads. If visibility is reduced while driving, turn on your lights and maintain a safe following distance. Intense lightning is likely with any thunderstorm that develops. Avoid driving through water on roads. Lightning kills and injures Canadians every year. Remember, when thunder roars, go indoors!
Severe thunderstorm warnings are issued when imminent or occurring thunderstorms are likely to produce or are producing one or more of the following: large hail, damaging winds, torrential rainfall.
The Office of the Fire Marshal and Emergency Management recommends that you take cover immediately if threatening weather approaches.