South Simcoe Forecast for Tuesday May 7 New Tecumseth, ON, Canada / FM92 South Simcoe Today Adrianne Proceviat May 7, 2024 | 6:42 AM Marc Dalmulder / CC Sunny today… High 22. Clouding over with showers beginning this evening… Might even get a thunderstorm… Low 9. A mix of sun and cloud tomorrow… Slight chance of showers… Possible thunderstorm… High 20.