Summer heat and humidity will get a head start on the actual arrival of the season which isn't until 4:50 p.m. on Wednesday.
Environment Canada is predicting an extended period of temperatures in the mid 30s and humidex values in the upper 30s to low 40s.
A heat warning has been issued from Parry Sound south to the Greater Toronto area, and that includes Barrie, Orillia and Simcoe County
Meteorologist Brad Rosseau tells Barrie 360 that overnight lows will make it challenging for sleeping if you don't have air conditioning or fans.
"Those overnight lows aren't really going to drop much below the 20 degree mark until you get later in the week, but even still with that said, your humidex values through the overnight are going to be in the high 20s to low 30s."
With the muggy conditions, there is an isolated threat over the next few days of showers and thunderstorms, though Rosseau says they will be pop-up, so not everyone will get raindrops.
He says it's important for people who are going to be outdoors or who struggle in extreme heat to use caution.
"Stay hydrated, first and foremost. If you do have any symptoms of heat stroke, get yourself checked out immediately. Always make sure to check on your neighbours, especially the elderly, as they can suffer the most during heat events, and do not leave pets or children in your vehicle."
If there is any consolation, we're going to bake along with millions of others this week.
"There's a really strong area of high pressure setting up off the Atlantic coast and when that happens, it kind of acts like a conveyor belt to move all that really warm and moist tropical air northward, so essentially that is what's happening across most of southern Ontario and across the northeast U.S."
By Friday, Rosseau expects a bit of a break in our region, with an overnight low in the upper teens and a daytime high around 30, though still quite muggy.
