From Environment Canada.

Tornado warnings for the following areas:

st. catharines – grimsby – northern niagara region
chatham-kent – rondeau park
dunnville – caledonia – haldimand
city of hamilton
niagara falls – welland – southern niagara region
mississauga – brampton
brantford – county of brant.
tornado warning – upgraded from a severe thunderstorm warning
for:
burlington – oakville
halton hills – milton.

updated or ended by 8:20 pm edt.
at 19:30 edt, radar shows thunderstorms possibly producing
tornadoes approaching the above regions.
this is a dangerous and potentially life-threatening situation.
emergency management ontario recommends that you take cover
immediately, if threatening weather approaches.