Friday, October 18th 2019, 6:56 am - A more significant show of cold weather towards Halloween has the potential to set off bands of significant lake-effect snow in the traditional snow belt regions of the Great Lakes.
While it may still be too early to answer the question, will it be dry for trick or treating on Halloween? we can talk about the temperature pattern for Halloween and where you will likely need extra layers to stay warm in your costume.
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As we look ahead to the final days of October, including Halloween, we expect a shift in the pattern that has dominated so far during October. The map below shows temperature anomalies through October 17 and the various shades of blue, green and purple highlight the widespread colder than normal temperatures across most of southern Canada. The focus of the coldest weather has been across the southern Prairies where temperatures have been 10 to 15 degrees colder than normal.
During the final week of October we expect that most of central Canada will be colder than normal, but the focus of the coldest weather relative to normal will shift east into the Great Lakes region.
Initially, the shots of chilly weather will only be a few degrees colder than normal, but we have the potential for a more significant shot of cold weather towards Halloween and continuing into early November.
This pattern also has the potential to set off bands of significant lake-effect snow in the traditional snow belt regions of the Great Lakes before the end of the month. As residents of this region well know, the first lake-effect snow of the year often comes during late October, and the upcoming pattern looks rather favourable for bringing a white Halloween to parts of the region.
So, for much of central Canada it looks like you will need an extra layer or two and possibly even boots for trick or treating. The regions with the best chance of being milder than normal for Halloween look to be near the B.C. coast, across Newfoundland and Labrador and across far northern areas of Canada, including Iqaluit.