More than 50 millimetres of rain landed on Toronto on Tuesday night and Wednesday morning, when Sarnia and Kitchener-Waterloo were reporting thunder and lightning.
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In London, the airport weather station registered a "strong thunderstorm" around 10 p.m. Tuesday and again at 10:25 p.m. More "strong thunderstorms" were reported from 1 a.m. to 3 a.m. Wednesday.
A strong downward movement of air called a downburst descended on Brampton early Wednesday morning, with winds up to 100 km/h splitting trees, uprooting hydro poles and tearing down part of a warehouse. The storm was earlier believed to have been a low-intensity tornado.
"A downburst doesn't sound as dangerous as a tornado, but it can be just as damaging," said CBC meteorologist Johanna Wagstaffe.
Temperatures are set to rise over the next few days, adding to the tropical feel. Temperatures are expected to reach 30 C Thursday.
Wet weather expected in N.B., N.S.
Farther east, wet weather was expected to reach New Brunswick and southern Nova Scotia early Wednesday evening.
"It's not a bad day for the Maritimes ahead of this rain, with increasing clouds this afternoon and a high 19 C for Fredericton," Scotland said.
Halifax was expected to get wet weather late in the evening and a high of 20 C on Thursday. There were expectations of five to more than 15 millimetres of rain Wednesday night for the Maritimes.