Extreme heat and humidity will arrive in Ontario on Monday and persist throughout the week, a heat wave that meteorologists warn will be "dangerous" and potentially record-breaking.

Temperatures will spike into the 30s across swaths of Canada this week, including much of Ontario, while humidex values could make it feel as hot as the mid-40s in areas including the Greater Toronto Area.

It will be unbearably hot in these areas from Monday through Friday, with meteorologists calling the system "dangerously hot," during its peak from Tuesday through Thursday. The Weather Network warns that it may be sweltering enough to even potentially break some records along the way.

Humidex ratings could exceed the 45.6 C record for monthly temperatures set on June 30, 2018. 

A heat warning was issued for Toronto by Environment and Climate Change Canada on Monday morning, cautioning that "a prolonged heat event will begin today" with "dangerously hot and humid conditions expected through most of the week."

The government weather agency warns that humidex values could soar as high as a sizzling 45 C during the days, with hot temps persisting during overnight hours.

"There will be little relief through the overnight as lows are expected to be 20 to 23 degrees Celsius with humidex values of 26 to 30," warns EnvironCan.

Those living and working closer to Lake Ontario should have it a bit easier, with Environment Canada stating that "temperatures and humidex values may be several degrees cooler near the shores of the Great Lakes."