The Niagara Peninsula is currently under the influence of a high-pressure system anchored over New Brunswick, which is pushing a ridge over the Niagara Peninsula and should provide some decent, mostly sunny weather for today. With 850-hPa temps around 10 C, we should be able to reach about 23 C (mid-70s F) this afternoon. Tonight, expect clouds lows around 13 C (mid-50s F).

Friday, as the high organizes better and establishes a more southeasterly flow over the area, cooler, much more moist air will enter the region. High temperatures for tomorrow afternoon will drop into the 20 C (upper-60s F) range, by far the coolest part of the weekend. The major threat of rain will begin Friday night, though it’s not expected to be anything like a washout, more like on the order of 5 mm (0.2″). Low temperatures will remain in the 13 C ballpark Friday night and into early Saturday morning. Rain will clear out around Saturday afternoon, and temperatures will rebound fairly nicely, back up to around 23 C, as another sprawling high like the ones we’ve seen a lot of this August and September moves into the area. The result is that Saturday and Sunday will have fair skies, lows holding steady around 13 C and highs for Sunday perhaps reaching as high as 25 C (upper 70s F).

For perspective, the average temperature for this time of year is 22 C.