St. Catharines Weather Forecast
- Tonight – A few clouds. Low 12.
- Saturday – A mix of sun and cloud. 30 percent chance of showers late in the afternoon with risk of a thunderstorm. High 26 except 20 near Lake Ontario. Humidex 30. UV index 8 or very high.
- Saturday Night – Mainly cloudy. 30 percent chance of showers early in the evening with risk of a thunderstorm. Low 11.