Eastern Ontario hammered by storms - heat persists in Montreal

It was Ottawa's turn on Canada Day, as torrential rain turned parts of the city into a lake, including Highway 417 above at Bayshore Road. Record rainfall amounts exceeded 110mm in just a few hours as storms trained over the National Capital Region for hours. (OPP East Photo)

Heat Warning in effect for Montreal.

Severe Thunderstorm Watch issued for southwestern Quebec.

Another severe thunderstorm watch has been issued for the Montreal region on Thursday. Fortunately for flood weary parts of southern Quebec, the activity has remained west of the city over the last 48 hours across hard-hit Eastern Ontario. That may change Thursday.

Temperatures continue to be dangerously hot across a large portion of eastern Canada, with highs soaring into the middle 30s and humidex values in the middle 40s.

The high heat and humidity spawned several clusters of severe thunderstorms on Canada Day, with hours of torrential rain in the Ottawa region. The storms forced cancelation of the Canada Day celebrations on Parliament Hill, as well as many local events. The rain also set a July record for Ottawa, with 111.4mm falling in just a few hours. Like Montreal two weeks ago, that amount of water was too much for the urban sewer system to handle. Numerous roads and homes were flooded, with widespread damage to cars and basements reported.

More flooding in the central part of Ottawa near Highway 416. (OPP)

On top of the flash flooding, strong winds, over 100km/h in places, knocked down trees and power lines in a wide area from the Ottawa River south to the St. Lawrence Valley and west into southern parts of the province. Over 100,000 customers lost power between Ontario and far western Quebec.

The storms prompted tornado warnings for the second consecutive day. They also generated over 20,000 lightning strikes from Ontario south into upstate New York.

So what can we expect Thursday? More of the same, isolated strong to severe thunderstorms. This time, they may be a little closer to Montreal or even north of the city. The high for Montréal is forecast at 33C (92F). Overnight lows will be warm and muggy in the middle 20s. 

More heat is expected on Friday, up to 34C (94F). Some relief is forecast for Saturday in southwestern Quebec, as a weak cold front arrives with lower dew points behind it thus slightly less-humid. Warm temperatures however are expected to remain into next week.