The areas with the highest severe weather frequency in the province of Ontario are Southwestern (Windsor, Chatham corridor) and Central Ontario (Simcoe County, including the city of Barrie). Both areas often get amplified storms resulting from the Lake Breeze Front convergence.

Windsor has the most lightning strikes per year in Canada, and London is one of the most active areas in the country for storms.

In a typical year, Ontario averages 11 or more confirmed tornado touchdowns, with the highest frequency in southwestern Ontario.

In Northern Ontario, some tornadoes go undetected by ground spotters because of the sparse population and remote landscape; they are often discovered after the fact by aircraft pilots, where aerial observations of damaged forest confirm occurrences.

Tropical depression remnants can cause copious rains and winds in the south, but are rarely deadly. A notable exception was Hurricane Hazel in October 1954.

• Aug 2 2006 there were 14 confirmed tornadoes in Ontario
• There are approximately 120 severe weather events on Ontario each season
• Season runs from late April to early October and includes:
  • 70 damaging winds events
  • 20 heavy rain and flooding weather events
  • 20 hail producing events
  • 11 tornadoes (on the low side of the estimate)
• An F5 hit Elie, Manitoba 22 June 2007
• Ontario tornadoes are typically an F0-F1
• Ontario is overdue for an F2, they usually occur every 2 years
• Ontario is overdue for an F3, they usually occur every 8 yrs
• Ontario is overdue for an F4, they usually occur every 15 yrs or so, the last one was 25 years ago