As Canadians in Southern Ontario gear up for the Victoria Day long weekend the unofficial kickoff to summer—Mother Nature has other plans. A powerful line of severe thunderstorms is set to sweep through Toronto, Hamilton, and London, Ontario, tonight, bringing damaging winds, heavy rain, and a rollercoaster forecast for the holiday weekend. Whether you’re planning a barbecue, fireworks, or a cottage getaway, here’s your guide to navigating the weather with insights from The Weather Network, Environment Canada, and local experts. 

Tonight’s Severe Thunderstorm Warning

A severe thunderstorm warning is in effect for Southern Ontario, with a fast-moving line of storms expected to hit after midnight. From London, Ontario weather to Hamilton weather and Toronto weather, residents should brace for damaging wind gusts up to 100 km/h, torrential downpours dropping 10–20 mm of rain, and frequent lightning. “This is a potent system,” warns CTV London Meteorologist Julie Atchison. “The storms will start in London and race eastward toward Toronto and the GTA by early morning.”

For EU readers, think of this as akin to the intense summer storms that sweep across Germany or the Netherlands—sudden, powerful, and potentially disruptive. Environment Canada urges checking The Weather Network or weather.gc.ca for real-time updates, as conditions can shift rapidly. A severe thunderstorm watch may precede the warning, signaling that dangerous storms are brewing. Apps like TheWeatherNetwork are lifesavers for tracking weather network Toronto or weather Hamilton alerts on the go.

The stakes are high after the 2022 Canadian derecho, a monster storm that struck during the Victoria Day long weekend, toppling trees and cutting power to over a million homes. To avoid a repeat, secure outdoor furniture, charge devices, and keep emergency supplies handy—think water, snacks, and a flashlight. As one X user in Toronto put it, “The weather here is like a drama queen—calm one minute, chaos the next!”

Friday’s Turnaround

By Friday morning, the severe thunderstorms will be a memory, replaced by glorious sunshine and summer-like warmth. Temperatures will climb to 27°C, feeling closer to 31°C with the humidex, and southwest winds will keep things breezy. “It’s a beautiful day to shake off the storm,” Atchison says. Whether you’re in Toronto, Hamilton, or London, Friday is perfect for patio lunches, park walks, or prepping for the long weekend.

This dramatic shift is classic Southern Ontario weather—unpredictable yet vibrant. For EU readers, it’s like the Netherlands’ fickle spring days, where rain gives way to sun in hours. Posts on X capture the mood, with Toronto weather fans joking, “From thunderstorm apocalypse to beach day in 12 hours—only in Ontario!” If you’re planning outdoor activities, seize Friday before the weather cools for the Victoria Day long weekend.

Victoria Day Long Weekend Forecast

The Victoria Day long weekend—celebrated on Monday, May 19, 2025—brings cooler temperatures and mixed weather. Here’s the breakdown for Toronto, Hamilton, and London, Ontario:

• Saturday: Cloudy with a 40% chance of showers. Highs of 20°C make it mild but damp. Pack rain gear for Toronto’s Victoria Day parades or Hamilton’s community festivals.
• Sunday: Cloudy and cooler at 16°C. Fireworks might face challenges, so check weather network Toronto or weather London Ontario for updates.
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• Monday: Sunny with a high of 17°C—ideal for barbecues or cottage trips. It’s the holiday’s best day for outdoor fun.
• Tuesday: A mix of sun and cloud, hitting 18°C. A pleasant end to the long weekend.

This forecast, backed by Global News and The Weather Network, reflects Southern Ontario’s spring volatility. Unlike the balmy Victoria Day of 2023, when Toronto hit 29°C, this year’s cooler vibe may shift plans indoors. For EU readers, it’s similar to planning a Whitsun holiday in the UK—hope for sun, but expect rain.