The heat wave that has gripped the western Prairies for the past week with temperatures in the mid to upper thirties will be spreading east over southern Manitoba beginning this weekend. A ridge of high pressure over southern Manitoba on Thursday will move east into the Great Lakes by Friday. A return southerly flow west of the ridge will draw increasingly warm air from the western U.S. and Canada into southern MB over the weekend, with temperatures expected to climb into the low to mid thirties by Sunday. The hot weather is expected to continue through much of next week with temperatures likely persisting in the thirties most of the week. Little precipitation is expected over the period, except for a possibility of some showers or thunderstorms Tuesday and Wednesday as a weak cold front tries to move through southern MB.
Officially, a heat wave is defined as a period of at least 3 consecutive days with maximum temperatures of 32C or greater. This is a throwback from the Fahrenheit days when we used 90F (32C) to define a "hot" day. Unofficially, we have started to define a heat wave in Canada as a period of 3 days or more with maximum temperatures of 30C or more. It's a nice round number, and it's a good threshold for most Canadians to define as a "hot" day. Either way you slice it, it looks like an extended period of hot weather is coming to southern MB!