TORONTO July 5, 2025 – A heat warning has been issued by Environment and Climate Change Canada for Toronto and southern Ontario for the second time in two weeks, with humidex values reaching 40 are expected for the next 2 days starting Saturday afternoon and into Sunday evening.
Daytime highs of 31 to 33 degrees Celsius and a humidex of 40 are expected over the next 24-48 hours or so. Overnight lows of 21 to 25 degrees Celsius, providing little relief from the heat. Temperatures are expect to lower a little on Monday to a seasonal 27 degrees celsius.
With this hot and muggy air can Toronto area residents can expect deteriorating air quality with the Air Quality Health Index approaching the high risk category.
Here are the areas affected by the heat warning:
Simcoe – Delhi – Norfolk; Dunnville – Caledonia – Haldimand; Watford – Pinery Park – Eastern Lambton County; Sarnia – Petrolia – Western Lambton County; Chatham-Kent – Rondeau Park; Windsor – Leamington – Essex County; London – Parkhill – Eastern Middlesex County; Strathroy – Komoka – Western Middlesex County; St. Thomas – Aylmer – Eastern Elgin County; Rodney – Shedden – Western Elgin County; Woodstock – Tillsonburg – Oxford County; Brantford – County of Brant; City of Toronto; Uxbridge – Beaverton – Northern Durham Region; Newmarket – Georgina – Northern York Region; Pickering – Oshawa – Southern Durham Region; Vaughan – Richmond Hill – Markham; Midland – Coldwater – Orr Lake; Orillia – Lagoon City – Washago; Barrie – Collingwood – Hillsdale; Fenelon Falls – Balsam Lake Park – Northern Kawartha Lakes; Apsley – Woodview – Northern Peterborough County; Lindsay – Southern Kawartha Lakes; Peterborough City – Lakefield – Southern Peterborough County; City of Hamilton; Owen Sound – Blue Mountains – Northern Grey County; Saugeen Shores – Kincardine – Southern Bruce County; Hanover – Dundalk – Southern Grey County; Wingham – Blyth – Northern Huron County; Listowel – Milverton – Northern Perth County; Goderich – Bluewater – Southern Huron County; Stratford – Mitchell – Southern Perth County; Mount Forest – Arthur – Northern Wellington County; Guelph – Erin – Southern Wellington County; Kitchener – Cambridge – Region of Waterloo; Innisfil – New Tecumseth – Angus; Shelburne – Mansfield – Northern Dufferin County; Orangeville – Grand Valley – Southern Dufferin County; Caledon; Mississauga – Brampton; Halton Hills – Milton; Burlington – Oakville; St. Catharines – Grimsby – Northern Niagara Region; Niagara Falls – Welland – Southern Niagara Region
Those living in these southern Ontario communities are advised to take action to protect yourselves and others – extreme heat can affect everyone’s health.
Know the signs of heat Illness
Determine if you or others around you are at greater risk of heat illness. Check on older adults, those living alone and other at-risk people in-person or on the phone multiple times a day. Watch for the early signs of heat exhaustion in yourself and others. Signs may include headache, nausea, dizziness, thirst, dark urine and intense fatigue.
Here’s what you should do if you have symptoms of heat stroke
Stop your activity and drink water. Heat stroke is a medical emergency! Call 9-1-1 or your emergency health provider if you, or someone around you, is showing signs of heat stroke which can include red and hot skin, dizziness, nausea, confusion and change in consciousness.
While you wait for medical attention, try to cool the person by moving them to a cool place, removing extra clothing, applying cold water or ice packs around the body. Drink water often and before you feel thirsty to replace fluids.
Close blinds, or shades and open windows if outside is cooler than inside. Turn on air conditioning, use a fan, or move to a cooler area of your living space.
How to stay cool
If your living space is hot, move to a cool public space such as a cooling centre, community centre, library or shaded park. Follow the advice of your region’s public health authority. Plan and schedule outdoor activities during the coolest parts of the day. Limit direct exposure to the sun and heat. Wear lightweight, light-coloured, loose-fitting clothing and a wide-brimmed hat.
Car heat safety
Never leave people, especially children, or pets inside a parked vehicle. Check the vehicle before locking to make sure no one is left behind.
For more information: How to protect yourself from the health effects of extreme heat Health risks and who is at risk of extreme heat events.
Other articles from totimes.ca – otttimes.ca – mtltimes.ca