Heat and humidity 'dangerous' as temperatures forecast to reach 33 C and feel like 45 in Hamilton

Temperatures in Hamilton will reach 33 C and feel like 45 with humidity Sunday, Environment Canada forecasts. 

"The first significant heat event of the season with dangerously hot and humid conditions will begin this afternoon and is expected to continue into the week," the federal agency said on its website Sunday morning.

All of southern Ontario and much of southern Quebec are under heat warnings.

In and around Hamilton, the extreme heat is forecast to last through Tuesday, with overnight lows of 21 C to 25 C "providing little relief from the heat."

Environment Canada warns that depending how things go, high temperatures may continue through Wednesday.

Cool spaces open, indoor public swims free in Hamilton 

The medical officer of health for the city initiated a heat warning starting Sunday. As a result, the city and some community agencies will open cooling areas for people to go during the "dangerous" heat and humidity, medical officer of health Elizabeth Richardson said in a statement Saturday. As well, regularly scheduled public swims at indoor pools will be free of charge.

In Burlington, Ont., public libraries will be available for cooling during regular hours, that city said in a statement Saturday.

To reduce the risk of heat-related illness, Richardson recommends people:

• Drink plenty of water, avoiding alcoholic and caffeinated beverages. 

• Go to an air-conditioned place. 

• Wear light, loose-fitting clothing. Wear a hat or take an umbrella to keep your head cool and wear sunscreen.

• Limit physical activities during the day. 

• Take a cool bath or shower.

• Close your blinds or curtains. Open windows to let air circulate when using a fan.

• Never leave children or pets alone in closed vehicles. 

• Check on your neighbours and family.

Signs and symptoms of heat exhaustion include heavy sweating, weakness, cold, pale and clammy skin, a weak pulse, fainting and vomiting, Hamilton public health says, adding anyone experiencing symptoms should seek help right away. 

Temperatures will be about 9 C hotter than average

Landlords can help decrease the risk of heat-related illness for tenants by checking if their units have adequate cooling and providing them access to a cool space, Hamilton public health says.

Apartment buildings in particular can trap heat and become dangerously hot, hence attempts in recent years to force property owners to cool units, including in Hamilton and Toronto. 

Overall, maximum temperatures in Hamilton over the coming days will be about 9 C hotter than average, when compared to data from 1981 to 2010, according to CBC's Climate Dashboard. Minimum temperatures will be about 5 C hotter than average. 

The dashboard predicts that if current fossil-fuel-emissions trends continue, the average annual temperature is likely to increase by 2.6 C to 4.8 C in Hamilton by the end of the century.

An April Hamilton public-health committee report identified wards 2, 3 and 4 as areas in which people are most vulnerable to heat exposure. The staff report found there were 53 emergency department visits for heat-related illness among Hamiltonians between May and September in 2024. An analysis found higher rates of heat-related emergency visits among residents who lived in poorer areas.

There were an average of two hospitalizations per year for heat-related illness between May and September from 2015 to 2024. There had not been a heat-related death recorded since 2011, when there were two.