Humidity and thunderstorms forecast to return to Montreal

The weather this past weekend was perfect for whatever outdoors plans you had. I chose the 37th Annual Granby Antique Car Show in the Eastern Townships. A perfect venue, light breeze, low humidity and bright sunshine resulted in hundreds of cars on display and thousands of spectators.

After an absolutely perfect weekend, with full sunshine, low humidity and temperatures in the middle 20s, showers and thunderstorms will be on the increase today to end July. High pressure dominated the weather across southern Quebec, giving us a very rare stretch this summer with no rain. A frontal system will begin to impact Montreal today, signalling a change in the air mass. We can still expect partial sunshine, but with isolated showers and thunderstorms developing in eastern Ontario this afternoon, and moving into southern Quebec late in the day. The biggest threat from any developing thunderstorms will be heavy rain, as some cells will be slow moving.

The high temperature today, and through the entire week, will be in the 27C to 30C range (80 to 85F). As the month draws to a close, Montreal has yet to record a 30C high temperature. Normally we have 5 such days, with July 2016 featuring 6 days above 30C. Overnight lows this week will be on the mild side, around 19C (66F), In addition to the warm temperatures, humidity levels will be on the rise, reaching oppressive levels by Thursday. The risk for showers and thunderstorms will exist each day this week, peaking late Friday with the arrival of a cold front. At this time, next weekend looks decent, with clearing skies, cooler temperatures and low humidity.

The weather has been very active across North America over the past week. Heavy rain and thunderstorms occurred across a portion of the middle Atlantic states, with numerous reports of flash flooding. Meanwhile, the weather remains hot and dry across western Canada, with strong thunderstorms occurring along the periphery of the heatwave in Saskatchewan and Manitoba. Temperatures soared into the upper 30s on Sunday, with Assiniboia, Saskatchewan, a little Prairie town I am very familiar with, reaching 37.7C or 99.8F. Mankota, Saskatchewan, near the Montana border, was the warmest placer in Canada on Sunday, reaching 38.2C (101F).