South Simcoe Forecast for Thursday April 18 New Tecumseth, ON, Canada / FM92 South Simcoe Today Adrianne Proceviat Apr 18, 2024 | 6:32 AM Cloudy with scattered showers… Mix of sun and cloud this afternoon… High 16. Mainly cloudy with showers this evening… Low 8. Showers ending tomorrow afternoon… Remaining cloudy… High 13.