Brisk northwest winds have ushered in an unseasonably cool airmass over Southern MB today with temperatures only in the single digits early this afternoon. Normal highs for this time of year are around 18-19C, so we're a good 10 degrees below "normal". With an expected high of only 11c this afternoon, this will be only a couple degrees above the coldest high ever for Sept 11th which was 8.9C back in 1890. (NOTE: this is corrected from an earlier post, which incorrectly stated the coldest Sept 11 was 15.6C back in 1949.. I was looking at the wrong column!) The cool northerly winds have even produced some bands of lake effect rainshowers off Lakes Manitoba and Winnipeg with Beausejour picking up 1.5 mm of rain off Lake Winnipeg this morning.
With such a cool airmass in place, it would seem likely that frost would be a concern for tonight.. However, a storm system from the west is expected to bring increasing clouds overnight with increasing southeasterly winds that should minimize the threat of frost over southern MB tonight. However, look for a chilly evening with patchy frost possible mainly east of Winnipeg. This storm system by the way may bring the season's first snowfall over central AB and SK tonight through Wednesday night!
No doubt about it.. fall is here!