South Simcoe Forecast for Wednesday May 8 New Tecumseth, ON, Canada / FM92 South Simcoe Today Adrianne Proceviat May 8, 2024 | 6:38 AM Eli Christman / CC A mix of sun and cloud this morning… Clouding over by this afternoon, chance of showers, possibly a thunderstorm… High 20. Partly cloudy this evening… Low 8. Sunny with cloudy periods tomorrow… High 15.