2024 British Columbia floods
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(2 days)
Northwestern Washington, United States
 Flooding in Surrey, British Columbia during the storm. | |
| Date | October 18, 2024 – October 20, 2024 (2 days) |
|---|---|
| Location | Southern British Columbia, Canada Northwestern Washington, United States |
| Cause | Atmospheric river |
| Deaths | 4[1][2] |
| Property damage | $110,000,000[3][4] |
For the most recent series of floods, see the 2025 British Columbia floods.
The 2024 British Columbia floods were a series of floods, debris flows, and mudslides caused by an atmospheric river that struck Southwestern British Columbia from October 18 to October 20, 2024. Four people were killed during the event, two in the Lower Mainland and two on Vancouver Island.
The storm also brought heavy snow to inland portions of the province with major highways having been closed. Northwestern Washington was on the southern edge of the atmospheric river. There, strong winds knocked out power to thousands and minor flooding led to road closures in some areas.
The low pressure system that produced the atmospheric river moved into Alberta during the following days leading to the first snowfall of the season in parts of that province.
A strong low pressure system developed in the Gulf of Alaska in the days leading up to the event, pulling a cold front along with it.[5] The motion of the low stalled the cold front and associated moisture plume with heavy rain being observed in the Lower Mainland and Vancouver Island. The Olympic Peninsula of Washington state also received heavy rain.[6]
The moisture reached southwestern British Columbia on October 18. It wasn't until October 20 when a new low pressure system captured the cold front and swept the system eastward. Chinook winds were observed in Alberta while heavy precipitation was falling in British Columbia before the system moved eastward and brought snow to Calgary and Edmonton on October 21.[7] This was Calgary's first snowfall of the season.[8]
Atmospheric river events are common in British Columbia and Washington during the cold season. September 2024 brought one to the North Coast that is believed to have been the most intense in the Northeastern Pacific in the satellite record that goes back to 2000.[9] Between British Columbia and Southeast Alaska, an average of 35 atmospheric rivers make landfall annually.[10]
Preparations
A couple days before the floods, Environment Canada issued a rainfall warning due to an atmospheric river expected to "drench the B.C. coast" through the weekend of October 18.[11][12] Official forecasts called for rainfall totals in excess of 200 mm (7.9 in) in some areas. The British Columbia River Forecast Centre issued flood watches for numerous areas and authorities highlighted the risk of landslides and power outages.[13][14]
Farmers and residents of the Sumas Prairie area between Abbotsford and Chilliwack were "preparing for the worst." This area was especially hard hit by and still recovering from the 2021 Pacific Northwest floods, which were caused by a series of atmospheric rivers.[15]
The timing of the atmospheric river coincided with the 2024 British Columbia general election on October 19. Elections BC engaged in preparations ahead of the event to ensure voting accessibility by having power and paper backups in place in case of power outages. A record number of people participated in early voting for the election, limiting the storm's impact.[16]
