Ontario · live outlook · refreshes every 3 h

Ontario sap flow forecast

The next several days for Ontario's sugaring country, read the way a sugarmaker reads them: how cold the night gets, how warm the afternoon gets, and whether that adds up to a run.

Ontario highlighted on a map of the maple belt, with its forecast towns (Lanark, Elmira, St. Joseph Island) marked — Ontario in the maple beltDots: Lanark · Elmira · St. Joseph Island

Season opens: February (southwest) to March (north); typical
Closes: early April; typical

Lanark · Lanark County, southwest of Ottawa, is billed as 'Ontario's Maple Syrup Capital' (Destination Ontario).

Forecast for Lanark

Updated Nov 10, 5:00 AM EST

3 sap days in the next 6

freeze thaw 0 °C

WedNov 11
2° / 7°
No refreeze forecast
Low of 36°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.
ThuNov 12
0° / 6°
No refreeze forecast
Low of 32°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.
FriNov 13
-3° / 6°
Classic sap day
Low 27°F, high 43°F — nights in the 20s and days in the 40s: the textbook sap day.
SatNov 14
-2° / 6°
Classic sap day
Low 28°F, high 43°F — nights in the 20s and days in the 40s: the textbook sap day.
SunNov 15
-2° / 7°
Classic sap day
Low 28°F, high 45°F — nights in the 20s and days in the 40s: the textbook sap day.
MonNov 16
0° / 5°
Run tapering
No overnight freeze (low 32°F). Yesterday's favorable weather may allow a run to continue, then slow without a refreeze.

Data: Environment and Climate Change Canada. Verdicts use freeze-thaw thresholds from maple field research; your woods may run a little differently.

Elmira · Southwestern Ontario reference point (Waterloo Region), the part of the province OMAFRA says taps earliest.

Forecast for Elmira

Updated Nov 10, 5:00 AM EST

1 sap day in the next 6

freeze thaw 0 °C

WedNov 11
1° / 10°
No refreeze forecast
Low of 34°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.
ThuNov 12
1° / 7°
No refreeze forecast
Low of 34°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.
FriNov 13
-2° / 5°
Classic sap day
Low 28°F, high 41°F — nights in the 20s and days in the 40s: the textbook sap day.
SatNov 14
-1° / 7°
Maybe a light run
Only a light freeze (30°F). Branches may not freeze hard enough for a strong run.
SunNov 15
-1° / 8°
Maybe a light run
Only a light freeze (30°F). Branches may not freeze hard enough for a strong run.
MonNov 16
1° / 6°
No refreeze forecast
Low of 34°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.

Data: Environment and Climate Change Canada. Verdicts use freeze-thaw thresholds from maple field research; your woods may run a little differently.

St. Joseph Island · Northern Ontario sugarbush area named by Destination Ontario; OMAFRA says northern regions tap 2–3 weeks after the southwest.

Forecast for St. Joseph Island

Updated Nov 10, 5:30 AM EST

Only marginal days ahead

freeze thaw 0 °C

WedNov 11
4° / 7°
No refreeze forecast
Low of 39°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.
ThuNov 12
-2° / 1°
Maybe a light run
A cool 34°F high. The thaw may be too brief for much flow.
FriNov 13
-4° / 1°
Maybe a light run
A cool 34°F high. The thaw may be too brief for much flow.
SatNov 14
-3° / 3°
Maybe a light run
A cool 37°F high. The thaw may be too brief for much flow.
SunNov 15
0° / 5°
No refreeze forecast
Low of 32°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.
MonNov 16
1° / 7°
No refreeze forecast
Low of 34°F — no refreeze is forecast. An earlier run may continue, then slow; temperature alone cannot rule out flow.

Data: Environment and Climate Change Canada. Verdicts use freeze-thaw thresholds from maple field research; your woods may run a little differently.

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Your sugarbush, your forecast

Hourly temperatures for your exact spot, turned into a day-by-day sap-run outlook. US and Canada.

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Other provinces

Data & method · 4

1.MSC GeoMet — city page weather · Environment and Climate Change Canada
2.Sap flow in sugar maple: timing and weather drivers (Frontiers in Agronomy, 2025) · de Lima Santos et al.
3.Maple Sugaring Tips for Beginners and Backyard Maple Sugar Producers · UNH Extension
4.North American Maple Syrup Producers Manual, 2nd ed. (Bulletin 856) · The Ohio State University Extension

LuckySap · free on iPhone & Android

Never miss the first run

LuckySap can ping you the evening before a strong sap day, then keeps your collections, sugar readings and boils in one season log. Free on iPhone and Android.