Missing rain: Ontario’s October could end among the driest on record
After a rainy year, this October was oddly dry across Ontario. We look at why this month could finish among the province's driest Octobers, and when we can expect a pattern flip that will bring much-needed precipitation.
Ontario's weather has taken a dramatic turn, shifting from a record-shattering, wet summer to an unusually dry October, with some areas nearing historic lows for rainfall.
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We look at why this month could finish among the province's driest October, and when we can expect a pattern flip that will bring much-needed precipitation
The numbers: How dry is dry?
Toronto (YYZ): With only 15 mm of rain, this October could rank as the fourth-driest on record, and the driest since 2000, when 17.6 mm was recorded.
Hamilton (YHM): Just 25 mm, and this October could be the sixth-driest since 2000 when 37 mm was recorded.
Ottawa (YOW): A meagre 14 mm, and if October ended today, it would be the third-driest on record, and driest since October 2000 when 27.6 mm of rainfall fell.
Sault Ste. Marie (YAM): One of the lowest stations in Ontario, measuring just 9 mm, with the city facing the driest October since 2000 (40.9 mm).
Precipitation deficit: How much rain is ‘missing?'
Rainfall in Toronto, Hamilton, and Ottawa is expected to remain below 50 per cent of normal, with less than 10 mm likely through the rest of October –– an alarmingly low total considering the time of year.
Northern Ontario is seeing the most striking anomaly, with Sault Ste. Marie receiving a mere eight per cent of its typical October rainfall.
The dominant pattern across Ontario has been one with an absent storm track. A large ridge of high pressure has been anchored over New England, Ontario and Quebec, keeping precipitation leaving most of the region well below normal.
The forecast: Will it stay dry?
The forecast for the next 10 days suggests the dry spell will continue, with southern Ontario expected to end the month more than 20 mm below-normal rainfall.
Northern Ontario has better rainfall prospects, either normal or slightly above normal to finish off October.
Early indications highlight a return to normal precipitation patterns across southern Ontario as we flip the calendar into November.
Impacts
The prolonged dry spell has pushed fire danger to elevated levels, an unusual concern for late-October when wetter conditions are typically expected.
At the end of September, there were pockets of abnormally dry regions across southwestern Ontario and moderate drought conditions speckled across northern Ontario.
In total, 22 per cent of Ontario is under drought conditions and 41 per cent of the province is abnormally dry.
Conclusion
There’s hope that a pattern shift in early November could finally bring the much-needed rainfall to southern Ontario, but now, the region faces one of its driest Octobers in decades.
This will likely be the driest October across Ontario since the year 2000.
Climate connection
Looking at the current pattern, the dry pattern hasn’t been this widespread across Ontario since at least 2000.
The driest October since 1960 goes to October of 1963 with very significant precipitation deficits provincewide.
One of the wettest Octobers on record occurred in 1995 when multiple stations picked up more than 150 mm of precipitation including Hamilton, Ottawa, Sault Ste. Marie and Welland.