Residents of Sarnia, Ontario, can expect a cloudy Tuesday before the weather clears up for a sunny mid-week stretch. Environment Canada forecasts cloudy skies for July 28, 2026.
As of 11:00 a.m., conditions at the Sarnia Chris Hadfield Airport were already cloudy with a temperature of 21.5°C and humidity at 89 percent, making it feel like 29 with the Humidex. Winds were from the north-northwest at 21 km/h, gusting to 30 km/h. The high today is expected to reach 24°C, with the Humidex climbing to 31.
Winds are forecast to pick up later, with north winds at 30 km/h gusting to 50 km/h tonight and similar gusty conditions continuing into Wednesday, when gusts could reach 60 km/h. No weather alerts are in effect for the Sarnia-Lambton County region.
The outlook improves quickly after today. Wednesday and Thursday will both be sunny with highs of 24°C and 25°C, respectively. By Friday, temperatures are set to jump to a high of 29°C under sunny skies. This warm-up lines up with Environment Canada’s summer forecast for southern Ontario, which called for hotter-than-normal conditions and extra humidity for June, July, and August.
The weekend brings a return to cloudier weather. Saturday is expected to be cloudy, with a 40 percent chance of showers arriving Saturday night, and Sunday will see a 30 percent chance of showers. Today’s UV index is rated high at 6, and Wednesday’s index will be very high at 8, so sun protection will be important during the sunny days ahead.
