Thunderstorms ease heat and humidity in southern Quebec

A gust front along the leading edge of thunderstorms swept a wall of dust and debris across the Trans-Canada Highway around 1:45pm Tuesday afternoon. Winds gusted between 50 and 90km/h with this storm. (ValleyWeather Photo)

Strong thunderstorms swept across southern Quebec Tuesday afternoon, helping to ease the heat and humidity present since the weekend. Temperatures have been soaring into the low 30s, with little relief during overnight hours, as lows only dropped only into the low 20s. The 4 day heatwave generated heat warnings across Ontario and Quebec, with humidex values approaching 40C.

The storms produced very little rain in Montreal, with only 1mm falling at my home on Ile Perrot. The wind was the big story, gusting up to 90km/h in many locations in southern Quebec, and generating a wall of dust as the storm swept across Dorval and Ville Saint Laurent around 1:45 p.m. There were reports of small hail in Vaudreuil-Dorion, and as many as 48,000 hydro clients were without power at the height of the storm. That number is down to 17,000 as of 9pm Tuesday night. In Rigaud, lightning struck a tree knocking it onto a tent trailer at Camp Choisy. Two injuries were reported.

Slightly cooler weather is expected for the balance of the week, with much lower dew points and humidity. A few lingering instability showers are possible Wednesday, with nothing but sunshine Thursday and Friday. Highs will be in the upper 20s.

The high temperature in Montreal on Tuesday was 31C (88F) before the storms swept in. This marks the 14th day this month with highs at or above 30C. It has been a very warm and windy month, with only half the normal precipitation. Between 40 and 50mm of rain have fallen in Montreal, but most of that occurred in just a few hours on July 11th.