Heat wave moving through southern Ontario

A heat warning is now in effect for Toronto and parts of the Greater Toronto Area, as the air quality in the region deteriorates.

At around 2 p.m., Environment Canada said a two-day heat wave will start Thursday, with daytime temperatures expected to be near 30 C today through Friday.

Overnight temperatures in Toronto are expected to be around the high teens tomorrow night, which the federal agency says can offer some relief from the blistering heat.

Max temperatures can reach as high as 31 C with minimum temperatures settling at around 17 C during this time.

The heat warning impacts southern parts of the province – including Hamilton, Vaughan, Pickering, Halton and Peel regions – and most of northeastern Ontario. 

On Wednesday morning, at around 10:15 a.m., Environment Canada issued a special air quality statement, saying the air quality could pose a moderate risk to people in the area with the potential of increasing to high risk later in the day. Just before 10 p.m., the air quality statement ended.

The federal agency says the "hot and humid weather conditions" can lead to elevated levels of air pollution.

The statement is in effect for Toronto, Mississauga, Brampton, Vaughan, Richmond Hill, Markham, Halton Hills, Milton, Burlington, Oakville, Pickering, Oshawa, Newmarket Georgina, southern Durham Region and northern York Region.

In Toronto, Environment Canada says it is currently 27 C and can hit a high of 30 C, though it will be slightly cooler near Lake Ontario at a high of 22 C.

Some people may experience symptoms like increased coughing, throat irritation, headaches, or shortness of breath due to the air quality. Seniors, children, and those with cardiovascular or lung disease, like asthma, are “especially” at risk, Environment Canada says.

Anyone experiencing symptoms is encouraged to cut their time outside or reschedule strenuous outdoor activities until the special air quality statement is lifted.

“Stay inside if you have breathing difficulties,” the weather agency said in its statement, adding using an air conditioner that cools and filters air may help.

Opening the windows in your home may also let in more polluted air, Environment Canada said.

Northern parts of Ontario are currently experiencing a heat wave, with heat warnings in effect as temperatures are expected to hit a maximum of 32 C.

Despite the current heat, the Weather Network says Canada’s summer forecast is expected to be cooler compared to the last few years.

For most of Ontario, a “changeable summer” is expected, Weather Network said, with hot weather periods cooling off with frequent cold fronts. 

⚠️Special Air Quality Statement has been issued
🗺️Greater Toronto Area
⏲️This afternoon into early evening

Hot, sunny conditions expected to increase ground-level ozone concentrations.#AirQuality #BeAirAware #ONwx

Alerts👉 https://t.co/PDtm4m3fDt
AQHI👉https://t.co/UKLDPCiLZV pic.twitter.com/Ct5tJxxPWQ

— ECCC Weather Ontario (@ECCCWeatherON) May 31, 2023