A severe thunderstorm watch has now been issued for Niagara, on top of a heat warning.
Environment Canada says conditions are favourable for the development of severe thunderstorms that may be capable of producing strong wind gusts, large hail and heavy rain.
Forecasters say thunderstorms could occur this evening as well.
They are reminding residents that when thunder roars, go indoors.
Meantime, a heat warning continues for Niagara with a high of 34 but it will feel like 42.
Saturday will still be hot with a high of 34 before it cools off Sunday with a high of 24.