Tuesday marks the beginning of yet another streak of hotter temperatures for southern Ontario, marked by powerful storms that will peak during the overnight. The heat continues for most of the week, but a return to cooler days is ahead for Friday and the early part of the Labour Day long weekend. Read below for more.
- Clusters of thunderstorms gather through the evening and overnight
- Severe risk shifts east for Wednesday
- Three-day hot stretch begins Tuesday ahead of a cooler Sunday
- Keep on top of severe weather ALERTS in your area
TUESDAY: HUMIDITY RETURNS, WITH RISING OVERNIGHT STORM RISK
The brief reprieve of milder temperatures is behind us, as Tuesday marks the start of another stretch of hotter days, though briefer than those in the past. Daytime highs look to be in the mid-to-high 20s, but feeling into the 30s with the humidity.
It'll start off mostly dry, but things start changing in the afternoon, thanks to a low-pressure system in the U.S. and a cold front from the northwest moving into the region.
Much of southern Ontario is likely to see at least a shower into Wednesday, but there's some thunderstorm risk bundled into this setup as well, with some potential for severe storms as well.
Though parts of the southwest will already hear a rumble here and there by the afternoon, the strongest severe risk looks to be through the late evening hours, near the Windsor and Sarnia areas.
The storms will move east through the night, reaching the GTA overnight.
WEDNESDAY AND BEYOND: SEVERE RISK SHIFTS EAST, COOLDOWN INSIGHT
Some of those storms will still be ongoing early Wednesday morning, but it's the afternoon when severe storm risk starts building back in, with the strongest chance in eastern Ontario.
The humidity will have settled in quite thoroughly, boosting storm energy as a sharp cold front slices through, with a mid-afternoon to early evening time frame. Strong wind gusts are especially likely, and there will be just enough shear in the atmosphere to make for a slight tornado chance around the Ottawa Valley.
A combination of daytime highs and widespread humidity will keep things feeling like the 30s once again Wednesday, with more of the same Thursday.
Beyond, however, Friday sees a cold front descend through the province, bringing temperatures back down and sweeping away the humidity, setting the stage for a cool start to the Labour Day long weekend, with daytime highs in the low 20s.
Sunday will feature warmer temperatures, but for the week beyond, a pattern change looks to usher in a few days where parts of the north will get their first frosts, and even the temperate south will be feeling more like early fall.
Keep an eye on the forecast as we continue to monitor Ontario's weather outlook.