Strong thunderstorms followed by cooler weather

Cooler weather is on the way for the holiday weekend in Ontario and Quebec. (AccuWeather)

Severe Thunderstorm Watch in effect: Eastern Ontario and Western Quebec

The flood waters continue to rapidly recede on the Ottawa River, as the warmest air of the year to date invades southern Quebec. Our first taste of heat and humidity Wednesday, saw the mercury rise to 29.4C (85F) in Montreal, just shy of the record of 30.2C set in 1977. Thursday will be even warmer, with high temperatures expected in the low 30s. Today, we have an outside chance of the record in Montreal of 32.2C set in 1962. Sunshine will dominate most of the day, before a vigorous cold front arrives this evening. Behind the front much colder air will filter into southern Quebec, with temperatures falling back to the middle teens Friday and into the Victoria Day long weekend.

In advance of the cold front today, the St. Lawrence Valley will experience very strong southwest winds, in the 40 to 70km/h range. In addition to the wind, a line of strong to severe thunderstorms is expected to develop in Ontario this afternoon and reach southern Quebec between 6 and 8pm this evening. Some of the storms may produce heavy rain, hail and very strong winds. As of 11am Thursday morning, a severe thunderstorm watch has been posted in southern and eastern Ontario. The watch will likely be extended into Montreal this afternoon.

On Friday look for clearing skies, and much cooler temperatures, with highs near 17C (63F).

While we bake, a late spring snowstorm is blasting through the Rockies. This was the scene on Interstate 70 in Vail this morning. (CBS Denver)