Environment Canada has issued a severe weather alert for the City of Toronto ahead of a heat event that is expected to last from Saturday until Tuesday.

With a high of 27 C recorded today, we're headed into the weekend with dry and seasonable temperatures.

Sadly for those who hate sweating their makeup off within 5 minutes of leaving the house, things will start changing drastically overnight thanks to a "heat dome" in the central United States.

The Weather Network explained Friday morning that humidex values and temperatures will both rise consistently in Southern Ontario between now and Sunday, reaching a feels like temperature in the low 40s and hovering there until at least Monday.

We can blame the aforementioned heat dome, which Weather Network meteorologists describe as "a ridge of high pressure stationed in the upper atmosphere, acting as a vault to trap heat in."

The heat is on this weekend for much of Ontario, with humidex values to approach or hit the low-40s in many areas by Sunday 👉 https://t.co/anzTwLbxwV#ONwx #ONheat #ONstorm pic.twitter.com/C0DchxzKIv

— The Weather Network (@weathernetwork) July 24, 2020

"Heat can accumulate over days or weeks, turning the heat dome into a kind of self-perpetuating atmospheric cap over the landscape," writes Wired of the intense and perilous heat wave currently plaguing the continental U.S. 

"On a normal day, some of the sun's energy evaporates water from the soil, meaning that solar energy isn't put toward further warming the air. But as the heat dome persists, it blasts away the soil's moisture, and that solar energy now goes full-tilt into heating the air."

Environment Canada noted in a heat warning issued around 3:30 on Friday afternoon that Sunday and Monday "will feel particularly uncomfortable" with his in the low 30s and humidex values of 40 or higher.

"Hot and humid air can also bring deteriorating air quality and result in the air quality health index approaching the high risk category," writes the federal weather agency.

"Extreme heat affects everyone... Watch for the effects of heat illness: swelling, rash, cramps, fainting, heat exhaustion, heat stroke and the worsening of some health conditions."