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Wisconsin · county maple atlas

Maple sugaring in Brown County, Wisconsin

Brown County had 11 maple operations and 4,154 taps in the 2022 Census. Around Green Bay, sap usually runs from March 15 to April 9. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 160 days until the usual start.
Sap starts
Mar 15
typical year
Season ends
Apr 9
about 4 weeks
Sap days / season
32.5
1991–2026 average
Taps, 2022
4,154
#32 of 60 in WI

Sap-flow outlook at Green Bay right now

Full Wisconsin forecast →

Forecast for Green Bay, WI

Updated Oct 6, 9:36 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Brown County's season usually opens around March 15, which is 160 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    52° / 71°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    45° / 64°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    41° / 66°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    50° / 73°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    60° / 75°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    55° / 65°
    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 Bay

Freeze-thaw weather at Green Bay peaks in the weeks of Mar 2 to Apr 6, which hold about 46% of a season's sap days. March is the busiest month.
Typical season: Mar 15 – Apr 90246Week of Dec 1: 1.4 sap days on averageWeek of Dec 8: 1.5 sap days on averageWeek of Dec 15: 1.2 sap days on averageWeek of Dec 22: 1.2 sap days on averageWeek of Dec 29: 0.6 sap days on averageWeek of Jan 5: 0.8 sap days on averageWeek of Jan 12: 0.6 sap days on averageWeek of Jan 19: 0.4 sap days on averageWeek of Jan 26: 0.7 sap days on averageWeek of Feb 2: 1.0 sap days on averageWeek of Feb 9: 1.2 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: 2.1 sap days on averageWeek of Mar 9: 2.4 sap days on averageWeek of Mar 16: 2.7 sap days on averageWeek of Mar 23: 3.0 sap days on averageWeek of Mar 30: 2.8 sap days on averageWeek of Apr 6: 2.1 sap days on averageWeek of Apr 13: 1.5 sap days on averageWeek of Apr 20: 1.4 sap days on averageWeek of Apr 27: 0.5 sap days on averageWeek of May 4: 0.3 sap days on averageWeek of May 11: 0.1 sap days on averageWeek of May 18: 0.1 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 15
Average number of freeze-thaw sap days in each week of the season at Green Bay, 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 12; the middle half of seasons fell between Mar 3 and Mar 19. Earliest Feb 10 (2024), latest Mar 28 (2018).
Closing signal
Median Apr 12; middle half between Apr 4 and Apr 19. Earliest Mar 11 (2012), latest Apr 29 (2018).
Sap days by month
Dec17%Jan8%Feb16%Mar35%Apr23%May2%

36 seasons of sap weather

Brown County seasons, 1991–2026

The best sap year at Green Bay was 2002 with 52 freeze-thaw days; the leanest was 1998 with 22. 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 5 – Apr 8, 32 sap days3220252025: Mar 9 – Apr 9, 37 sap days3720242024: Feb 10 – Mar 12, 36 sap days3620232023: Mar 10 – Apr 9, 48 sap days4820222022: Mar 20 – Apr 20, 30 sap days3020212021: Mar 2 – Apr 4, 40 sap days4020202020: Mar 16 – Apr 19, 43 sap days4320192019: Mar 17 – Apr 20, 34 sap days3420182018: Mar 28 – Apr 29, 43 sap days4320172017: Mar 2 – Apr 1, 27 sap days2720162016: Mar 12 – Apr 14, 31 sap days3120152015: Mar 10 – Apr 11, 29 sap days2920142014: Mar 25 – Apr 23, 23 sap days2320132013: Mar 26 – Apr 24, 31 sap days3120122012: Feb 13 – Mar 11, 42 sap days4220112011: Mar 21 – Apr 21, 28 sap days2820102010: Feb 27 – Mar 30, 29 sap days2920092009: Mar 14 – Apr 16, 34 sap days3420082008: Mar 21 – Apr 16, 22 sap days2220072007: Feb 24 – Mar 21, 28 sap days2820062006: Mar 8 – Apr 9, 26 sap days2620052005: Mar 8 – Apr 4, 24 sap days2420042004: Mar 13 – Apr 15, 36 sap days3620032003: Mar 12 – Apr 13, 33 sap days3320022002: Mar 12 – Apr 7, 52 sap days5220012001: Mar 16 – Apr 18, 22 sap days2220002000: Feb 28 – Mar 16, 34 sap days3419991999: Mar 3 – Mar 27, 41 sap days4119981998: Mar 1 – Apr 5, 22 sap days2219971997: Mar 19 – Apr 22, 26 sap days2619961996: Mar 21 – Apr 24, 39 sap days3919951995: Mar 12 – Apr 15, 34 sap days3419941994: Mar 14 – Apr 11, 33 sap days3319931993: Mar 23 – Apr 27, 25 sap days2519921992: Mar 19 – Apr 12, 28 sap days2819911991: Mar 3 – Apr 3, 29 sap days29
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Green Bay. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Brown County in the Census of Agriculture

USDA counts maple operations every five years. In Brown County the 2022 Census found 11 farms making syrup (+38% since 2017). That works out to about 0.33 gallons of syrup per tap in 2022. Among the 385 counties in this atlas, Brown County ranks 208 by taps.

Brown County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
2022114,1541,3610.33
20178withheldwithheld—

“Withheld” means USDA suppressed the figure to avoid disclosing data for individual operations; the farm count is still published.

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 Bay (594ft), 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

Brown County sugaring questions

When should I tap maple trees in Brown County, Wisconsin?
In a typical year the sap starts running around March 15 near Green Bay and the season winds down around April 9. 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 10 and as late as Mar 28.
How much maple syrup does Brown County produce?
The 2022 Census of Agriculture counted 11 maple operations in Brown County with 4,154 taps producing 1,361 gallons of syrup, ranking 32 of 60 Wisconsin's counties with published tap counts.
How many sap days does Brown County get in a season?
On average 32.5 freeze-thaw sap days from December through May at Green Bay, of which about 12.6 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2002 (52 sap days); the leanest was 1998 (22).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Green Bay (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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