Ontario

Guelph Swelters Under Week-Long Heat Wave, Humidex to Hit Low 40s

By

boringnews
June 29, 2026 4:55 pm

Guelph, Ontario, is set to bake under a prolonged heat wave this week, with Environment Canada issuing a Heat Warning for the city and southern Wellington County. Daytime highs are forecast to reach 31 to 33 degrees Celsius from Tuesday, June 30, through at least Friday, July 3, with humidex values pushing into the low 40s. Wednesday and Thursday are expected to be the hottest days, potentially hitting 34 to 36 degrees Celsius.

The Environment Canada alert warns of a “long duration heat event” that will offer little relief overnight, with lows only dipping to 21 to 24 degrees Celsius. The heat event may continue into Saturday, July 4. The timing falls right over Canada Day on July 1, when many residents have outdoor plans.

The extreme weather is being driven by a heat dome that formed over the eastern United States, its northern edge reaching into the Great Lakes region. While communities right along the lakes may get a slight break from cooler water temperatures, inland areas like Guelph will feel the full brunt. The Weather Network notes that Pearson International Airport could see a feels-like value of 44 on Canada Day, likely challenging the site’s hottest Canada Day on record.

With the oppressive heat and high humidity creating dangerous conditions, Wellington-Dufferin-Guelph Public Health has activated its ClimateSafe Map. The online tool points residents to cooling centres, splash pads, libraries, and community spaces where they can escape the heat. City-run warming and cooling centres are open during heat warnings.

Residents are urged to stay hydrated, avoid strenuous activity during peak afternoon hours, and seek out air-conditioned spaces. A check on elderly neighbours or those without cooling at home can make a big difference. Some relief may be on the horizon later in the week.

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