From frost to hot weather for Ontario & Quebec

The view of a near perfect Sunday from Portsmouth Harbor Light in New Hampshire. (ValleyWX)

It is a chilly start for the week across much of southern Ontario & Quebec with frost reported once again in several locations. It is early for this as it does remain summer! It was as cold as 5C (41F) at my home on L'Ile Perrot this morning with 0C (32F) in Sherbrooke. We will see a sunny day with increasing southwest winds and warming highs into the low 20's. The wind shift will herald the arrival of much warmer air from the southwest that will invade Ontario and Quebec through the midweek. The heat and humidity may be record breaking for some of us with near 30C forecast for many areas by Wednesday and as warm as 33C in Toronto. A warm front will approach Montreal on Tuesday but may remain just south of the city with showers and clouds keeping the temperature a little lower for the city.

In any event it will lift well north of my location here in southern coastal New Hampshire. Wednesday will be a true September gift with sunshine and forecast highs of near 90F here. Who would have thought beach weather in September! The warmth will be short lived with more chilly air and the threat for frost moving into the region by next weekend.

With the arrival and departure of the warm and humid air, we have a pretty good chance of some strong thunderstorms Tuesday through Thursday along both the warm front and cold front. This will have to be monitored closely.