Grimsby, Ontario can expect a mild week with temperatures reaching the high 20s, along with scattered showers and possible thunderstorms through Wednesday, according to Environment Canada. There are no weather alerts in effect for the region as of Monday evening.
As of 5:00 PM EDT Monday, August 31, 2026, conditions at Vineland Station showed a temperature of 23.9°C with a humidex of 34, high humidity, and light winds. The forecast calls for highs of 28°C on Tuesday and 29°C on Wednesday, with a 40 percent chance of showers both days and the risk of thunderstorms.
The Weather Network is pointing to a stronger thunderstorm risk Tuesday afternoon when the temperature could feel like 42°C with the humidity. Wednesday evening has a 70 to 80 percent probability of showers, with another risk of strong thunderstorms.
By Thursday, conditions should begin to improve, with a 30 percent chance of showers and a high of 26°C. Friday and the weekend look drier, with a mix of sun and cloud and highs between 23°C and 25°C. These temperatures are close to Grimsby’s usual early September average high of 23°C.
Residents planning outdoor activities are advised to keep an eye on the sky, especially Tuesday and Wednesday, but no watches or warnings are currently in place for the St. Catharines – Grimsby – Northern Niagara Region, according to Environment Canada.
