More rain fell on Ottawa in 2 days than in a typical August

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A shelf cloud was spotted on Highway 138 near Moose Creek, Ont., southeast of Ottawa on Sunday, Aug. 7, 2022, as storms passed through the region. (Connor Mockett/Twitter - image credit)
A shelf cloud was spotted on Highway 138 near Moose Creek, Ont., southeast of Ottawa on Sunday, Aug. 7, 2022, as storms passed through the region. (Connor Mockett/Twitter - image credit)

More rain fell on Sunday, Monday and Tuesday than Ottawa typically sees in the entire month of August, according to Environment Canada.

About 48 millimetres of rain fell on Sunday after starting around noon as multiple storm cells passed through the region, senior climatologist David Phillips said by phone Tuesday.

A heat warning had been issued Friday, followed by a rainfall warning Sunday morning.

The rainfall continued Monday with occasional misty and cloudy breaks, dropping another 58 millimetres.

After those 106 millimetres of rain, precipitation continued Tuesday morning and was expected to end around noon, Phillips said. Amounts for Tuesday are not yet available.

On average, Ottawa sees about 85 millimetres of rain in the entire month of August.

"So ... even if doesn't rain another drop of rain in Ottawa all of August, it'll still come out to be about 30 per cent, 31 per cent more precipitation than you normally would get."

Looking back over 133 years of weather records collected in the city, only once has it rained more over two days in August: the 4th and 5th in 1981, when 116 millimetres fell, Phillips said.

A warm summer overall, but precipitation close to normal

While it's been a warmer-than-usual summer so far, there's been a "very close" to normal level of precipitation, unlike elsewhere in southern Ontario, Phillips said.

"I think farmers are happy, gardeners are happy ... it's been almost an ideal kind of situation," he said.

One of the effects of climate change is storms dumping more and more rain when it rains. Warmer air can hold more moisture, after all — about seven to 12 per cent more per degree, Phillips said.

He cautioned against attributing any specific weather event to climate change, but said that overall, statistics bear out that "when nature chooses to rain, we normally get more precipitation.

"And so I think that fits that particular situation that we saw on the on the weekend," Phillips said.