A special weather statement has been issued for Niagara.
Environment Canada says thunderstorms with pea to nickel size hail are possible today.
"Isolated thunderstorms are expected today as a cold front moves through. The main threats will be hail of 1 to 2 cm and wind gusts up to 70 km/h."
Weather will clear for the holiday Monday with a mix of sun and cloud expected in the afternoon with a high of 24 feeling more like 27 with the humidex.