Many Tornado Warnings have passed through southern Ontario today, starting in London and making their way through Toronto and Durham.
Environment Canada says they’ve been tracking a severe thunderstorm that could produce a tornado.
Toronto and the surrounding areas were under a Tornado Warning.
That Warning has since been changed to a Severe Thunderstorm Watch.
There is no watch or warning in effect for Niagara currently, however there is a chance of showers or thunderstorms overnight and tomorrow.
Warnings are an urgent message that severe weather is either occurring or will occur, whereas watches indicate that there's potential for the severe weather to occur.