Wet Southern Ontario Summer Named Among Top Weather Stories of 2024

Southern Ontario’s wet summer featured among Environment Canada’s top 10 weather stories of 2024, while Alberta experienced no less than four of this year's most impactful events. 

Selected and ranked based on such factors as severity, and human and economic impact, the annual top 10 weather stories of the year are compiled by Environment Canada’s meteorological services team. The 2024 top 10 list was released earlier this month. 

The soggy southern Ontario summer came in at No. 6 on the list, with two rain events particularly standing out.  

The first was a band of thunderstorms July 15-16 which dropped 50-60 mm of rain on the London area, flooding roads and basements, and closing a stretch of Highway 402 west of the city. Further east, over 60 mm of rain fell over six hours in the Hamilton and Burlington areas, flooding homes, streets, and businesses. In downtown Toronto, 25 millimetres of rain fell in under one hour, flooding two subway stations along with parts of Lakeshore Boulevard. On the morning of July 16, storms lined up across southern Ontario once again, but this time, they aimed squarely at the Greater Toronto Area (GTA), flooding several 400 series highways.   

By the time the rain ended, the floods of July 15-16 had caused over $940 million in insured damages across southern Ontario. 

The second event occurred just weeks later, between August 17 and 18, as a slow-moving low-pressure system brought another round of severe flooding to the region. Toronto Pearson International Airport received a record-breaking 128.3 millimetres of rain in a single day. Meanwhile, Billy Bishop Airport, less than 20 kilometres away, stayed dry, highlighting the often-isolated nature of thunderstorm rains. 

The floods of August 17 and 18 across the GTA and surrounding regions caused over $100 million in insured losses, bringing the combined cost of flood damage across the region to over $1 billion for the year. It marked the second-costliest summer in Ontario history for weather-related damage after the Toronto floods of 2013. 

Portions of eastern Ontario and Quebec were also deluged by the No. 2 weather event on the list, the 2024 hurricane season, as the remnants of hurricanes Beryl and Debby in early July and August, both triggered significant flooding. In a 24-hour period, portions of the St. Lawrence River Valley received up to 200 mm of rain from Debby. 

Alberta was home to the top weather story of the year for 2024, the heatwave and subsequent wildfires that badly damaged the town of Jasper in July. 

On the other end of the spectrum was the No. 3 weather event, the January deep freeze that saw temperatures in parts of Alberta as well as B.C. plunge to near-50 degrees C with the windchill. Alberta saw about 125 daily minimum temperature records, including eight all-time cold records broken between January 10 and 17. 

No. 5 on the list was the early August hailstorm that battered homes and vehicles in parts of Calgary before moving off to the southeast, carving a swath through maturing crops, known by prairie farmers as “the great, white combine.”  

Finally, making the list at No. 9 was the mid-June temperature extremes that brought scorching weather to the parts of eastern Canada but below normal readings in Western Canada. In fact, Alberta set 46 daily record lows across the province between June 15 and 20.