Are tornadoes considered severe weather or extreme weather?

They can actually be either depending on their intensity. ECCC defines warm-season severe weather as tornadoes, wind gusts reaching 90 km/h or greater, hail having diameter 2 cm or greater, or 50 mm of rain in an hour or less (note - is less in some regions). These phenomena occur many times per year across Canada and are considered a regular part of our warm season climate.

However, climatologically extreme weather can also occur - that is, severe weather phenomena having a size or intensity that has been very rarely if ever observed. Examples are violent tornadoes (EF/F4 to EF/F5) and softball-sized or larger hail that can only be generated by extremely intense supercell thunderstorms. An event may also be considered extreme if it is climatologically rare for a certain location or time of year.