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Wisconsin · county maple atlas

Maple sugaring in Green Lake County, Wisconsin

Green Lake County had 14 maple operations and 1,990 taps in the 2022 Census. Around Green Lake, sap usually runs from March 11 to April 4. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 156 days until the usual start.
Sap starts
Mar 11
typical year
Season ends
Apr 4
about 3 weeks
Sap days / season
34.8
1991–2026 average
Taps, 2022
1,990
#36 of 60 in WI

Sap-flow outlook at Green Lake right now

Full Wisconsin forecast →

Forecast for Green Lake, WI

Updated Oct 6, 10:31 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Green Lake County's season usually opens around March 11, which is 156 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    53° / 70°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    46° / 65°

    0h below · 24h above

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

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    49° / 74°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    57° / 76°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    53° / 67°
    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 Green Lake

Freeze-thaw weather at Green Lake peaks in the weeks of Mar 2 to Apr 6, which hold about 49% of a season's sap days. March is the busiest month.
Typical season: Mar 11 – Apr 40246Week of Dec 1: 1.3 sap days on averageWeek of Dec 8: 1.6 sap days on averageWeek of Dec 15: 1.3 sap days on averageWeek of Dec 22: 1.1 sap days on averageWeek of Dec 29: 0.7 sap days on averageWeek of Jan 5: 1.0 sap days on averageWeek of Jan 12: 0.7 sap days on averageWeek of Jan 19: 0.5 sap days on averageWeek of Jan 26: 0.9 sap days on averageWeek of Feb 2: 1.1 sap days on averageWeek of Feb 9: 1.1 sap days on averageWeek of Feb 16: 1.7 sap days on averageWeek of Feb 23: 1.8 sap days on averageWeek of Mar 2: 2.4 sap days on averageWeek of Mar 9: 2.6 sap days on averageWeek of Mar 16: 3.3 sap days on averageWeek of Mar 23: 3.5 sap days on averageWeek of Mar 30: 2.9 sap days on averageWeek of Apr 6: 2.2 sap days on averageWeek of Apr 13: 1.4 sap days on averageWeek of Apr 20: 1.1 sap days on averageWeek of Apr 27: 0.3 sap days on averageWeek of May 4: 0.1 sap days on averageWeek of May 11: 0.1 sap days on averageWeek of May 18: 0.0 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 11
Average number of freeze-thaw sap days in each week of the season at Green 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 8; the middle half of seasons fell between Feb 28 and Mar 14. Earliest Feb 9 (2024), latest Mar 26 (2018).
Closing signal
Median Apr 7; middle half between Apr 1 and Apr 15. Earliest Mar 11 (2012), latest Apr 29 (2018).
Sap days by month
Dec16%Jan10%Feb16%Mar37%Apr20%May1%

36 seasons of sap weather

Green Lake County seasons, 1991–2026

The best sap year at Green Lake was 2018 with 53 freeze-thaw days; the leanest was 2017 with 21. 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: Feb 23 – Mar 29, 33 sap days3320252025: Feb 26 – Apr 2, 43 sap days4320242024: Feb 9 – Mar 16, 49 sap days4920232023: Mar 9 – Apr 7, 43 sap days4320222022: Mar 17 – Apr 17, 38 sap days3820212021: Feb 28 – Apr 3, 39 sap days3920202020: Mar 5 – Apr 6, 49 sap days4920192019: Mar 13 – Apr 16, 33 sap days3320182018: Mar 26 – Apr 29, 53 sap days5320172017: Feb 26 – Apr 2, 21 sap days2120162016: Mar 7 – Mar 28, 31 sap days3120152015: Mar 7 – Apr 4, 25 sap days2520142014: Mar 18 – Apr 18, 32 sap days3220132013: Mar 24 – Apr 21, 28 sap days2820122012: Feb 12 – Mar 11, 41 sap days4120112011: Mar 15 – Apr 5, 25 sap days2520102010: Feb 27 – Mar 30, 28 sap days2820092009: Mar 12 – Apr 16, 36 sap days3620082008: Mar 16 – Apr 16, 24 sap days2420072007: Feb 23 – Mar 21, 35 sap days3520062006: Mar 7 – Apr 9, 31 sap days3120052005: Mar 4 – Apr 3, 33 sap days3320042004: Mar 4 – Apr 7, 40 sap days4020032003: Mar 8 – Apr 10, 31 sap days3120022002: Mar 10 – Apr 7, 48 sap days4820012001: Mar 11 – Apr 4, 25 sap days2520002000: Feb 28 – Mar 15, 40 sap days4019991999: Feb 26 – Mar 27, 35 sap days3519981998: Feb 24 – Mar 25, 23 sap days2319971997: Mar 11 – Apr 14, 28 sap days2819961996: Mar 18 – Apr 18, 39 sap days3919951995: Mar 9 – Apr 10, 37 sap days3719941994: Mar 11 – Apr 8, 32 sap days3219931993: Mar 20 – Apr 22, 31 sap days3119921992: Mar 16 – Apr 13, 39 sap days3919911991: Mar 2 – Apr 2, 35 sap days35
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Green Lake. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Green Lake County in the Census of Agriculture

USDA counts maple operations every five years. In Green Lake County the 2022 Census found 14 farms making syrup (+250% since 2017), with taps +170% and syrup output +220% over the same five years. That works out to about 0.13 gallons of syrup per tap in 2022 (0.11 in 2017). Among the 385 counties in this atlas, Green Lake County ranks 251 by taps.

Green Lake County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
2022141,9902660.13
20174736830.11

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 Green Lake (810ft), 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

Green Lake County sugaring questions

When should I tap maple trees in Green Lake County, Wisconsin?
In a typical year the sap starts running around March 11 near Green Lake and the season winds down around April 4. 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 9 and as late as Mar 26.
How much maple syrup does Green Lake County produce?
The 2022 Census of Agriculture counted 14 maple operations in Green Lake County with 1,990 taps producing 266 gallons of syrup, ranking 36 of 60 Wisconsin's counties with published tap counts.
How many sap days does Green Lake County get in a season?
On average 34.8 freeze-thaw sap days from December through May at Green Lake, of which about 11.9 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2018 (53 sap days); the leanest was 2017 (21).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Green 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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