Snow is expected to return to parts of eastern Canada this week as a colder air mass moves across Ontario, Quebec and Atlantic Canada.
The most likely areas for early-season accumulation are northern Ontario and western Quebec, where temperatures are expected to fall close to or below freezing as precipitation moves through.
Some communities north of Timmins could see their first measurable snow of the season, while areas farther south are more likely to experience a mix of rain, wet snow and showers.
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Where snow is most likely
The developing pattern is tied to a cold front moving through eastern Canada at the start of the workweek.
As colder air arrives, rain may change to snow Sunday evening into Monday morning in portions of northern Ontario and western Quebec.
Higher terrain and locations farther north will have the best chance of seeing snow accumulate.
In lower-elevation communities, warmer ground temperatures could limit accumulation even if snow briefly falls.
The forecast remains sensitive to the exact track of the system and the timing of the cold air.
Small changes could determine whether precipitation falls mainly as rain, wet snow or accumulating snow in communities near the transition zone.
Snowfall totals remain uncertain
There is not currently a basis for describing this as a widespread major snowstorm across southern Canada.
Instead, the immediate concern is a narrow band of early-season snow in northern areas, with generally light accumulation possible in communities where temperatures remain cold enough.
Residents should rely on local forecasts for the latest accumulation estimates because conditions can vary considerably over short distances during autumn storms.
Environment and Climate Change Canada’s alert system separates snowfall warnings from other weather advisories, including frost and wind alerts.
A snowfall warning is issued only when forecast snow amounts or impacts reach the applicable regional threshold.
Frost and strong winds also part of the pattern
The cold air behind the front has already produced frost concerns across parts of Ontario, Quebec and New Brunswick.
Environment Canada advisories warned that temperatures could fall near the freezing mark, creating a risk to plants, trees and crops in exposed areas.
In Quebec’s James Bay region, a separate wind warning called for northwesterly gusts of up to 90 kilometres per hour on Monday.
Those winds could affect exposed roads, shorelines and outdoor structures even in places that receive little or no snow.
What residents should watch for
- Rain changing to wet snow Sunday night or Monday in northern Ontario and western Quebec.
- Slippery roads on untreated surfaces where temperatures fall below freezing.
- Frost damage to gardens, crops and outdoor plants.
- Rapidly changing conditions in areas near the rain-snow line.
- Updated local warnings from Environment and Climate Change Canada.
Drivers travelling through northern Ontario or Quebec should be prepared for reduced visibility and temporary slush on roads, particularly overnight and during the early morning.
Because pavement and ground temperatures are still relatively mild in many areas, not every burst of snow will lead to lasting cover.
Accumulation is more likely on grassy surfaces, untreated roads and elevated terrain.
What happens next
The system will continue to move through eastern Canada during the first half of the week, with precipitation gradually ending in some areas as colder and drier air arrives.
Forecast confidence is higher for a noticeable temperature drop and frost than for precise snowfall totals in southern communities.
Further updates will depend on the storm track, the depth of the cold air and whether precipitation remains long enough for snow to build up.
For now, the developing weather pattern signals an early reminder that winter conditions can begin in northern Canada well before sustained snow reaches major southern cities.
Frequently Asked Questions
Where is snow most likely in eastern Canada this week?
The best chance is in northern Ontario and western Quebec, especially communities north of Timmins and higher-elevation areas.
Will Toronto, Ottawa or Montreal receive accumulating snow?
The current pattern is more favourable for northern areas. Southern cities could see rain or wet snow, but lasting accumulation is less certain.
When could rain change to snow?
The transition is most likely Sunday evening into Monday morning as colder air moves across eastern Canada.
Are snowfall warnings in effect across Canada?
Weather alerts vary by region. Residents should check Environment and Climate Change Canada for current snowfall, frost, wind and other advisories.
What should drivers do during the early-season snow?
Slow down on untreated roads, allow extra stopping distance and check local forecasts before travelling through northern Ontario or Quebec.
Fact-Checked: Key weather details were checked against Environment and Climate Change Canada alert information and current Canadian forecast resources.
Disclaimer: Forecast details can change quickly, especially near the rain-snow transition zone; consult local alerts before travelling.