Wicked thunderstorms cool off one hot city

Just one of the hundreds of lighting strikes over L'Ile Perrot late Monday afternoon. The atmosphere was charged with energy after a very hot and humid day that saw highs in the lows 30s and humidex values over 40C. (ValleyWeather Image)

The hot summer of 2018 has rolled into August, with little relief so far. On Monday, Montreal reached 31.7C (89F), the fifteenth 30C plus day so far this summer. Adding to the extreme heat was oppressive humidity levels, with the humidex over 40C (104F) for 6 consecutive hours on Monday. The blazing daytime heat and humidity was brought to an abrupt end around the supper hour, as a line of fast moving thunderstorms crossed the city. The storms affected my domain on L'Ile Perrot close to 6pm, turning day to night, with a vivid display of spectacular lightning. Winds gusted over 90km/h at several locations, and 82km/h at Trudeau Airport. A much needed 10-20mm of rain fell over a 30 minute period from Valleyfield to Dorval.

The combination of strong winds and lightning knocked out power to over 40,000 Hydro Quebec clients, most across the West Island, Monteregie and South Shore. As of 11am Tuesday, 5600 clients remain without power.

Looking ahead to the remainder of this week, we can expect less humid weather, but still warm and somewhat unsettled. There is a risk of more showers and isolated thunderstorms today and Wednesday, but the risk is slight. On Thursday, skies should clear along with dryer air. The temperature will remain above normal, as it has all summer in Montreal. Expect daytime highs from 26C to 30C (79F to 86F) with overnight lows a little more comfortable, between 16C and 20C (61F to 68F). Skies will be partly to mostly sunny from Thursday through Sunday.