Wisconsin sap flow forecast

The next several days for Wisconsin'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. The season here usually opens mid-March.

Marathon County has the most taps in Wisconsin, 214,538 of 1,272,963 (16.9%; 2022 Census of Agriculture).

Forecast for Wausau

Updated Sep 26, 9:21 AM EDT

It's the off-season. Sap needs freezing nights, and there are none in sight. Wisconsin's season usually opens around March 15 — 170 days from now.

No freeze-thaw days in the forecast

Blue = below 32°F · Amber = thaw · dashed line = freezing

  1. SunSep 27
    67°high
    45°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 45°F — trees need a hard freeze to reload. No freeze, no run.

  2. MonSep 28
    73°high
    53°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 53°F — trees need a hard freeze to reload. No freeze, no run.

  3. TueSep 29
    70°high
    50°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 50°F — trees need a hard freeze to reload. No freeze, no run.

  4. WedSep 30
    68°high
    56°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 56°F — trees need a hard freeze to reload. No freeze, no run.

  5. ThuOct 1
    67°high
    54°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 54°F — trees need a hard freeze to reload. No freeze, no run.

  6. FriOct 2
    66°high
    46°low
    0h frozen
    20h thawed
    No freeze, no run

    Low of 46°F — trees need a hard freeze to reload. No freeze, no run.

Data: National Weather Service. Verdicts use freeze-thaw thresholds from maple field research; your woods may run a little differently.

Taylor County ranks second with 117,898 taps (9.3%; 2022 Census of Agriculture).

Forecast for Medford

Updated Sep 26, 6:31 AM EDT

It's the off-season. Sap needs freezing nights, and there are none in sight. Wisconsin's season usually opens around March 15 — 170 days from now.

No freeze-thaw days in the forecast

Blue = below 32°F · Amber = thaw · dashed line = freezing

  1. SunSep 27
    64°high
    48°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 48°F — trees need a hard freeze to reload. No freeze, no run.

  2. MonSep 28
    71°high
    51°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 51°F — trees need a hard freeze to reload. No freeze, no run.

  3. TueSep 29
    66°high
    50°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 50°F — trees need a hard freeze to reload. No freeze, no run.

  4. WedSep 30
    66°high
    53°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 53°F — trees need a hard freeze to reload. No freeze, no run.

  5. ThuOct 1
    64°high
    52°low
    0h frozen
    24h thawed
    No freeze, no run

    Low of 52°F — trees need a hard freeze to reload. No freeze, no run.

  6. FriOct 2
    63°high
    44°low
    0h frozen
    20h thawed
    No freeze, no run

    Low of 44°F — trees need a hard freeze to reload. No freeze, no run.

Data: National Weather Service. Verdicts use freeze-thaw thresholds from maple field research; your woods may run a little differently.

Somewhere else in Wisconsin?

Your sugarbush, your forecast

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

Planning ahead? Typical tapping dates for Wisconsin →

Data & method

  1. National Weather Service API — NOAA National Weather Service
  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

Never miss the first run

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