Dark clouds rolled over downtown Hamilton late Wednesday morning, unleashing heavy rainfall.
Environment Canada issued a severe thunderstorm warning around 10:45 a.m., just as the rain began. It later downgraded the warning to a thunderstorm watch by mid afternoon.
“Meteorologists are tracking a severe thunderstorm capable of producing very strong wind gusts, up to nickel size hail and heavy rain,” the weather agency said in a statement.
Torrential downpour was expected to dump as much as 50 mm of rain on the city in an hour, Environment Canada said. Wind gusts could’ve been up to 90 km/h.
The agency said the risk of thunderstorms continued into the early evening.
Brantford, St. Catharines, Niagara Falls and Burlington were also under a severe thunderstorm watch.
Environment Canada advised people to stay indoors.
It warned the heavy downpour may cause flash floods and water pooling on roads. Large hail could damage property and cause injury, it said. Strong gusts of wind might’ve tossed objects, damaged weak buildings, broken branches off trees and overturned large vehicles.
The Hamilton Conservation Authority said Wednesday it was on flood watch.
“Water levels and flows in all area watercourses are expected to increase significantly, as a result of the ongoing rain and thunderstorms occurring today,” it said in an email.
Residents should “exercise caution near all water bodies and structures such as bridges, culverts and dams during this time,” it added.