Humidity builds in Ontario before cooler temperatures, heavy rainfall arrive
Forecasters say that it will feel like autumn in parts of Ontario this week as cooler temperatures creep in.
Many regions in southern Ontario will see humid conditions on Monday, but an easterly wind will keep some areas cooler than others. Northwestern regions will still see a slight risk for active weather due to a slow-moving cold front. Details and timing, below.
THIS WEEK: HUMIDITY BUILDS BRIEFLY AHEAD OF UNSETTLED WEATHER AND PATTERN CHANGE
The cold front that contributed to the active weather seen in northwestern Ontario on Sunday will slowly move out of the region. However, there is a lingering non-severe storm risk that will continue on Monday morning and afternoon along the northern shores of Lake Superior.

Meanwhile, summer-like humidity will build in southern Ontario. This will allow for temperatures across the region to climb into the low and mid-20s, but feel like the low 30s in the afternoon.
However, an easterly wind off Lake Ontario will keep the GTA from getting overly warm, but temperatures will still be above seasonal and fair skies are expected.

A pattern change will slowly evolve by mid- to late-week, dropping temperatures to slightly below seasonal and introducing storms to parts of the south.
Tyler Hamilton, a meteorologist at The Weather Network, says that a frontal boundary will stall over southern Ontario mid-week and will bring heavy rainfall that could result in flooding in some areas.
A more autumnal pattern is anticipated late week, on the weekend and into next week.
Check back as we continue to monitor the forecast.
