A late, great taste of summer will soon be a distant memory across southern Ontario as the season’s first snowfall approaches the region heading into the final days of October.
It’s an abrupt change for many in southern Ontario who just enjoyed balmy, record-breaking overnight lows that were more common of July than the end of October.
Temperatures have fallen by as much as 15°C by Sunday, and cooler conditions settling in will set the stage for many areas to witness their first snows over the next couple of days.
A weak low-pressure system will develop along the frontal boundary that’s brought so much atmospheric upheaval to North America over the past week, including a rapid temperature drop and even a hefty first blanket of snow on much of the Prairies.
This system will draw some of that moisture north of the border, allowing precipitation to spill across southern and eastern Ontario overnight Sunday and into the day Monday.
Temperatures right around or just below freezing will allow much of that precipitation to change over to snow across cottage country and the National Capital Region.
While this system’s best snow will occur in southern Quebec, where places like Montreal may see their first snow before they’ve even seen their first frost, portions of Ontario are on track to see light accumulations overnight Sunday into the pre-dawn hours Monday morning.
Anyone driving through cottage country or eastern Ontario on Monday morning should exercise caution as some roads may be slick, especially where temperatures fall below the freezing mark.
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We’re looking ahead to another push of colder air moving into the Great Lakes region overnight Monday into Tuesday, which will crank up the lake-effect snow machine across the traditional snowbelts.
On-and-off snow showers are likely overnight Monday into Tuesday, and then again overnight Tuesday into Wednesday, as these cold winds blow over the relatively warm waters of Lake Superior, Lake Huron, and Georgian Bay.
Localized accumulations of 5-15 cm of snow are possible in these snowbelts, with the potential for a light dusting creeping close to the northern Greater Toronto Area through the middle of the week.
Check back for all the latest on conditions across Ontario.