Will the sap run this week?
Hourly forecasts from the National Weather Service and Environment Canada, turned into a plain-English sap-run outlook. No black box — you see the freeze and the thaw behind every call.
Your sugarbush, your forecast
Hourly temperatures for your exact spot, turned into a day-by-day sap-run outlook. US and Canada.
- 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°F, high over ~37°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.
- Too cold to run
- Never gets above freezing. The wood stays locked up.
- No freeze, no run
- Never drops below freezing. The tree can't reload.
Why no barometric pressure? Because the research doesn't support it: the Maple Syrup Producers Manual notes 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. Temperature crossing 32°F is what moves sap.
Get the alert the night before
LuckySap watches the forecast for your trees and can ping you the evening before a strong sap day — then logs every collection in seconds. Free on iPhone.
