State of emergency issued as 100-250+ mm of rain hits Ontario
Exceptional, multiple rounds of heavy rain led to localized flooding in parts of southern Ontario, with at least two locales recording more than 100 mm this weekend. And, as a result of recent flooding, a state of emergency was declared in St. Catharines, Ont.
To say it was a wet weekend in parts of Ontario is a bit of an understatement.
Multiple thunderstorms travelled along a stationary boundary draped across southern Ontario on Saturday and Sunday, dropping copious amounts of rainfall--especially in the Niagara region.
Grimsby, Ont., saw nearly 105 mm of rainfall, leading to localized flooding in many areas.

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The past two weeks have featured extremely uneven rainfall amounts across the province, varying significantly over relatively short distances.
As a result of the recent bouts of heavy rainfall and flooding, with 257.7 mm accumulated in the past seven days, the City of St. Catharines, Ont., declared a state of emergency on Monday.

The declaration comes after flooding caused significant damage to homes and properties over the past week.
Extreme rainfall totals this weekend
Hamilton airport: 65.1 mm
Third-wettest August day on record
Seventh-wettest day in history

Welland: 80.8 mm
Third-wettest August day on record
Fourteenth-wettest day in history
Grimsby: 104.8 mm
Second-wettest August day on record
Bancroft: 108 mm

The higher amounts were very localized along the Niagara Peninsula, from Oshawa to Cobourg, with narrowly heavy amounts extending towards the Ottawa area.
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In addition to the rainfall, the system spawned severe storms that briefly prompted a tornado a warning in the Niagara region. There was also a report of a possible tornado in Kemptville, Ont., with minor tree damage documented.
Rain-filled days in recent days

St. Catharines: 257.7 mm
Grimsby: 214.2 mm
Oakville: 95-110 mm
Barrie: 100-120 mm
Ottawa: 90-120 mm
Kitchener-Waterloo: 70-100 mm
Toronto: 50-70 mm
London: 40-60 mm
Windsor: 20-40 mm
Owen Sound: 20 mm