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Maple sap flow forecast

Will the sap run this week? We turn hourly forecasts into a plain-English sap-run outlook, and show the freeze and the thaw behind every call. No black box.

Try St. Albans, Lindsay or Le Granit.

Your sugarbush, your forecast

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

Live board

Is the sap running right now?

The map shades every region by its best day this week; the board below gives today’s and tomorrow’s call. Both read the forecast at the region’s first sugaring town. Green means a real freeze-thaw day.

Each region’s best day, today through Mon Nov 16. No sap day today; the first ones come in Maine (Thu Nov 12), New Brunswick (Thu Nov 12), Nova Scotia (Thu Nov 12), Illinois (Fri Nov 13), Iowa (Fri Nov 13), Ontario (Fri Nov 13), Kentucky (Sat Nov 14), Michigan (Sat Nov 14), Minnesota (Sat Nov 14), Missouri (Sat Nov 14), Wisconsin (Sat Nov 14), Pennsylvania (Sun Nov 15), West Virginia (Sun Nov 15), Massachusetts (Mon Nov 16), New Hampshire (Mon Nov 16).

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Best call in each region’s outlook, today through Mon Nov 16, at its first sugaring town (forecasts issued Nov 10, 7:36 AM EST)

  • Classic sap day
  • Sap likely
  • Maybe a light run
  • Run tapering
  • No freeze or no thaw

Each region is shaded by its best call from today through Mon Nov 16. 15 of 21 regions have a sap day in that time: Maine (Thu Nov 12), New Brunswick (Thu Nov 12), Nova Scotia (Thu Nov 12), Illinois (Fri Nov 13), Iowa (Fri Nov 13), Ontario (Fri Nov 13), Kentucky (Sat Nov 14), Michigan (Sat Nov 14), Minnesota (Sat Nov 14), Missouri (Sat Nov 14), Wisconsin (Sat Nov 14), Pennsylvania (Sun Nov 15), West Virginia (Sun Nov 15), Massachusetts (Mon Nov 16), New Hampshire (Mon Nov 16). Today the sap should run in 0. Connecticut: best maybe a light run on Sat Nov 14, today no refreeze forecast; Illinois: best classic sap day on Fri Nov 13, today no refreeze forecast; Indiana: best no forecast, today no forecast; Iowa: best classic sap day on Fri Nov 13, today no refreeze forecast; Kentucky: best classic sap day on Sat Nov 14, today no refreeze forecast; Maine: best sap likely on Thu Nov 12, today no refreeze forecast; Massachusetts: best sap likely on Mon Nov 16, today no refreeze forecast; Michigan: best classic sap day on Sat Nov 14, today no refreeze forecast; Minnesota: best classic sap day on Sat Nov 14, today no refreeze forecast; Missouri: best sap likely on Sat Nov 14, today no refreeze forecast; New Brunswick: best sap likely on Thu Nov 12, today maybe a light run; New Hampshire: best classic sap day on Mon Nov 16, today no refreeze forecast; New York: best maybe a light run on Wed Nov 11, today maybe a light run; Nova Scotia: best classic sap day on Thu Nov 12, today maybe a light run; Ohio: best no refreeze forecast on Wed Nov 11, today no refreeze forecast; Ontario: best classic sap day on Fri Nov 13, today no refreeze forecast; Pennsylvania: best classic sap day on Sun Nov 15, today no refreeze forecast; Quebec: best maybe a light run on Thu Nov 12, today no refreeze forecast; Vermont: best maybe a light run on Sat Nov 14, today no refreeze forecast; West Virginia: best classic sap day on Sun Nov 15, today no refreeze forecast; Wisconsin: best classic sap day on Sat Nov 14, today no refreeze forecast.

Not today, but 5 regions have a sap day tomorrow

Forecasts issued Nov 10, 7:36 AM EST

By region

Or pick your state or province

Each page checks the forecast at two or three real sugaring towns and refreshes every three hours.

United States

Canada

Reading the outlook

What each call means

Every day gets one of these, on the same six-step flow scale the LuckySap app uses.
Classic sap day
A night in the 20s, a day in the 40s. The textbook sap day.
Sap likely
A real freeze-thaw day (low under 30.2°F, high over 37.4°F), just outside the classic range.
Maybe a light run
It crosses 32°F, but barely. Maybe a light run.
Run tapering
No refreeze after a run. Sap keeps dripping for a day or so, slowing down.
Little thaw forecast
Never gets above freezing. The wood stays locked up.
No refreeze forecast
Never drops below freezing. The tree can't reload.

Why temperature, and why no barometric pressure?

Sap moves when the wood swings across freezing. A night below about 30.2°F (−1 °C) draws water up into the tree; a day above about 37.4°F (+3 °C) builds pressure and pushes it out of the taphole. In a field study, runs over a litre per tap came on days like that 94% of the time.

The Maple Syrup Producers Manual notes that most sap flows can be predicted reasonably well from air temperature alone, and we found no peer-reviewed study showing weather-scale pressure changes drive runs. So the outlook reads temperature, and shows you the numbers.

Planning further ahead? The when-to-tap pages have each region's typical season dates and year-by-year record, and the county atlas narrows them to 385 counties.

Run a sugarhouse, a maple association or a sugaring club? Put this forecast on your own website with one line of HTML. It's free.

Data & method · 5

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

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