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Wisconsin · county maple atlas

Maple sugaring in Washburn County, Wisconsin

Washburn County had 18 maple operations and 4,652 taps in the 2022 Census. Around Shell Lake, sap usually runs from March 17 to April 12. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 162 days until the usual start.
Sap starts
Mar 17
typical year
Season ends
Apr 12
about 4 weeks
Sap days / season
37
1991–2026 average
Taps, 2022
4,652
#29 of 60 in WI

Sap-flow outlook at Shell Lake right now

Full Wisconsin forecast →

Forecast for Shell Lake, WI

Updated Oct 6, 10:51 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Washburn County's season usually opens around March 17, which is 162 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    46° / 71°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    40° / 65°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    40° / 67°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    51° / 77°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    59° / 73°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    50° / 59°
    No refreeze forecast

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

When the sap runs

The sugaring calendar at Shell Lake

Freeze-thaw weather at Shell Lake peaks in the weeks of Mar 9 to Apr 6, which hold about 46% of a season's sap days. March is the busiest month.
Typical season: Mar 17 – Apr 120246Week of Dec 1: 0.9 sap days on averageWeek of Dec 8: 1.1 sap days on averageWeek of Dec 15: 0.8 sap days on averageWeek of Dec 22: 0.7 sap days on averageWeek of Dec 29: 0.3 sap days on averageWeek of Jan 5: 0.5 sap days on averageWeek of Jan 12: 0.3 sap days on averageWeek of Jan 19: 0.3 sap days on averageWeek of Jan 26: 0.7 sap days on averageWeek of Feb 2: 1.1 sap days on averageWeek of Feb 9: 0.9 sap days on averageWeek of Feb 16: 1.4 sap days on averageWeek of Feb 23: 1.5 sap days on averageWeek of Mar 2: 2.3 sap days on averageWeek of Mar 9: 2.8 sap days on averageWeek of Mar 16: 3.4 sap days on averageWeek of Mar 23: 4.0 sap days on averageWeek of Mar 30: 3.6 sap days on averageWeek of Apr 6: 3.3 sap days on averageWeek of Apr 13: 2.3 sap days on averageWeek of Apr 20: 2.2 sap days on averageWeek of Apr 27: 1.5 sap days on averageWeek of May 4: 0.6 sap days on averageWeek of May 11: 0.4 sap days on averageWeek of May 18: 0.2 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 17
Average number of freeze-thaw sap days in each week of the season at Shell Lake, 1991–2026. A sap day is an overnight low under 30.2 °F followed by an afternoon high over 37.4 °F. The shaded band is the typical season.

Year-to-year spread

Opening signal
Median Mar 14; the middle half of seasons fell between Mar 8 and Mar 22. Earliest Feb 15 (2012), latest Apr 3 (2013).
Closing signal
Median Apr 15; middle half between Apr 10 and Apr 25. Earliest Mar 11 (2012), latest May 4 (2013).
Sap days by month
Dec10%Jan5%Feb13%Mar37%Apr30%May4%

36 seasons of sap weather

Washburn County seasons, 1991–2026

The best sap year at Shell Lake was 2002 with 56 freeze-thaw days; the leanest was 2014 with 23. Seasons that start early tend to end early too: the trees run on the swing between freezing nights and mild days, and heat ends it.
JanFebMarAprMaysap days20262026: Mar 9 – Apr 11, 40 sap days4020252025: Mar 13 – Apr 17, 42 sap days4220242024: Mar 7 – Apr 7, 50 sap days5020232023: Mar 25 – Apr 27, 33 sap days3320222022: Mar 28 – Apr 28, 33 sap days3320212021: Mar 3 – Apr 3, 49 sap days4920202020: Mar 22 – Apr 25, 47 sap days4720192019: Mar 21 – Apr 16, 35 sap days3520182018: Mar 29 – Apr 29, 46 sap days4620172017: Mar 4 – Apr 8, 36 sap days3620162016: Mar 12 – Apr 14, 35 sap days3520152015: Mar 8 – Apr 11, 30 sap days3020142014: Mar 30 – Apr 26, 23 sap days2320132013: Apr 3 – May 4, 29 sap days2920122012: Feb 15 – Mar 11, 29 sap days2920112011: Mar 20 – Apr 24, 38 sap days3820102010: Feb 27 – Mar 30, 33 sap days3320092009: Mar 13 – Apr 15, 35 sap days3520082008: Mar 22 – Apr 16, 32 sap days3220072007: Mar 12 – Apr 16, 34 sap days3420062006: Mar 10 – Apr 10, 32 sap days3220052005: Mar 6 – Apr 8, 41 sap days4120042004: Mar 14 – Apr 15, 45 sap days4520032003: Mar 23 – Apr 10, 27 sap days2720022002: Mar 15 – Apr 10, 56 sap days5620012001: Mar 19 – Apr 19, 25 sap days2520002000: Feb 22 – Mar 29, 41 sap days4119991999: Mar 9 – Apr 13, 46 sap days4619981998: Mar 3 – Apr 5, 31 sap days3119971997: Mar 21 – Apr 25, 30 sap days3019961996: Mar 29 – May 3, 41 sap days4119951995: Mar 18 – Apr 20, 38 sap days3819941994: Mar 14 – Apr 12, 41 sap days4119931993: Mar 22 – Apr 26, 33 sap days3319921992: Mar 24 – Apr 28, 34 sap days3419911991: Mar 3 – Apr 2, 42 sap days42
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Shell Lake. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Washburn County in the Census of Agriculture

USDA counts maple operations every five years. In Washburn County the 2022 Census found 18 farms making syrup (-14% since 2017), with taps +15% and syrup output +55% over the same five years. That works out to about 0.18 gallons of syrup per tap in 2022 (0.13 in 2017). Among the 385 counties in this atlas, Washburn County ranks 198 by taps.

Washburn County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
2022184,6528300.18
2017214,0455350.13

Nearby

Neighboring maple counties

Distances are between reference towns; typical dates are each county's own estimate.

About these numbers

The season dates are estimated from 36 seasons of daily high and low temperatures for the PRISM 4-km grid cell at Shell Lake (1,220ft), scored with the same freeze-thaw rule as our live forecast: a sap day is an overnight low under 30.2 °F followed by an afternoon high over 37.4 °F. Each season's closing signal is the last sap day before accumulated warmth reaches a threshold, and the opening signal sits five weeks before that, never earlier than the first real freeze-thaw week. Tested against 117 state-seasons of USDA-reported dates, the rule lands within 5.5 days of the reported close and 6.6 days of the reported opening on average, and the typical dates shown here are scaled to Wisconsin's USDA record (12 years). Production figures are copied from the Census as published. Full method, calibration tables and the downloadable dataset →

Sources · 6

  1. 1.2022 Census of Agriculture, County Level Data — Wisconsin, Table 37: Maple Syrup, 2022 and 2017 · USDA National Agricultural Statistics Service
  2. 2.PRISM daily temperature grids (AN81d, 4 km), accessed 2026-10-05 · PRISM Group, Oregon State University, https://prism.oregonstate.edu
  3. 3.Applied Climate Information System (ACIS) web services · NOAA Regional Climate Centers
  4. 4.USDA NASS maple syrup reports — approximate average season opened and closed dates, 2011–2022 · USDA National Agricultural Statistics Service (mirrored by the University of Vermont)
  5. 5.Sap flow in sugar maple: timing and weather drivers (Frontiers in Agronomy, 2025) · de Lima Santos et al.
  6. 6.GeoNames gazetteer (cities500), CC BY 4.0 · GeoNames

FAQ

Washburn County sugaring questions

When should I tap maple trees in Washburn County, Wisconsin?
In a typical year the sap starts running around March 17 near Shell Lake and the season winds down around April 12. Have your taps in a day or two before the first forecast string of freezing nights and 40 °F days. In the past 36 seasons the weather signal came as early as Feb 15 and as late as Apr 3.
How much maple syrup does Washburn County produce?
The 2022 Census of Agriculture counted 18 maple operations in Washburn County with 4,652 taps producing 830 gallons of syrup, ranking 29 of 60 Wisconsin's counties with published tap counts.
How many sap days does Washburn County get in a season?
On average 37 freeze-thaw sap days from December through May at Shell Lake, of which about 9.1 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2002 (56 sap days); the leanest was 2014 (23).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Shell Lake (PRISM 4-km grid), scored with the same freeze-thaw rule as our live forecast, then calibrated against USDA's reported season dates for Wisconsin. They describe a typical year at one point in the county; your sugarbush, slope and elevation can shift them by days.

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