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Wisconsin · county maple atlas

Maple sugaring in Polk County, Wisconsin

Polk County had 47 maple operations and 54,930 taps in the 2022 Census. Around Balsam Lake, sap usually runs from March 16 to April 10. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 161 days until the usual start.
Sap starts
Mar 16
typical year
Season ends
Apr 10
about 4 weeks
Sap days / season
33.4
1991–2026 average
Taps, 2022
54,930
#9 of 60 in WI

Sap-flow outlook at Balsam Lake right now

Full Wisconsin forecast →

Forecast for Balsam Lake, WI

Updated Oct 6, 6:44 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Polk County's season usually opens around March 16, which is 161 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    46° / 70°

    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
    52° / 76°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    58° / 73°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    49° / 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 Balsam Lake

Freeze-thaw weather at Balsam Lake peaks in the weeks of Mar 2 to Apr 6, which hold about 53% of a season's sap days. March is the busiest month.
Typical season: Mar 16 – Apr 100246Week of Dec 1: 1.0 sap days on averageWeek of Dec 8: 1.1 sap days on averageWeek of Dec 15: 0.7 sap days on averageWeek of Dec 22: 0.6 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: 1.0 sap days on averageWeek of Feb 9: 0.9 sap days on averageWeek of Feb 16: 1.3 sap days on averageWeek of Feb 23: 1.4 sap days on averageWeek of Mar 2: 2.2 sap days on averageWeek of Mar 9: 2.4 sap days on averageWeek of Mar 16: 3.3 sap days on averageWeek of Mar 23: 3.6 sap days on averageWeek of Mar 30: 3.4 sap days on averageWeek of Apr 6: 2.8 sap days on averageWeek of Apr 13: 2.1 sap days on averageWeek of Apr 20: 1.9 sap days on averageWeek of Apr 27: 1.0 sap days on averageWeek of May 4: 0.4 sap days on averageWeek of May 11: 0.2 sap days on averageWeek of May 18: 0.1 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 16
Average number of freeze-thaw sap days in each week of the season at Balsam 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 13; the middle half of seasons fell between Mar 7 and Mar 20. Earliest Feb 15 (2012), latest Apr 2 (2013).
Closing signal
Median Apr 13; middle half between Apr 8 and Apr 20. Earliest Mar 11 (2012), latest Apr 29 (1996).
Sap days by month
Dec11%Jan6%Feb13%Mar38%Apr29%May3%

36 seasons of sap weather

Polk County seasons, 1991–2026

The best sap year at Balsam Lake was 2002 with 50 freeze-thaw days; the leanest was 2014 with 19. 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 8 – Apr 11, 35 sap days3520252025: Mar 10 – Apr 9, 40 sap days4020242024: Mar 6 – Apr 7, 45 sap days4520232023: Mar 22 – Apr 26, 30 sap days3020222022: Mar 26 – Apr 28, 31 sap days3120212021: Mar 2 – Apr 3, 42 sap days4220202020: Mar 21 – Apr 23, 39 sap days3920192019: Mar 20 – Apr 19, 32 sap days3220182018: Mar 29 – Apr 25, 43 sap days4320172017: Mar 2 – Apr 6, 33 sap days3320162016: Mar 7 – Apr 11, 34 sap days3420152015: Mar 7 – Apr 11, 26 sap days2620142014: Mar 27 – Apr 19, 19 sap days1920132013: Apr 2 – Apr 25, 24 sap days2420122012: Feb 15 – Mar 11, 22 sap days2220112011: Mar 17 – Apr 21, 31 sap days3120102010: Feb 27 – Mar 29, 24 sap days2420092009: Mar 13 – Apr 15, 33 sap days3320082008: Mar 20 – Apr 16, 31 sap days3120072007: Mar 13 – Apr 16, 30 sap days3020062006: Mar 9 – Apr 9, 25 sap days2520052005: Mar 5 – Apr 8, 39 sap days3920042004: Mar 13 – Apr 15, 40 sap days4020032003: Mar 23 – Apr 10, 24 sap days2420022002: Mar 14 – Apr 10, 50 sap days5020012001: Mar 19 – Apr 18, 23 sap days2320002000: Feb 21 – Mar 27, 39 sap days3919991999: Mar 7 – Mar 30, 41 sap days4119981998: Mar 2 – Apr 5, 26 sap days2619971997: Mar 20 – Apr 24, 28 sap days2819961996: Mar 27 – Apr 29, 40 sap days4019951995: Mar 13 – Apr 14, 34 sap days3419941994: Mar 14 – Apr 11, 43 sap days4319931993: Mar 20 – Apr 22, 32 sap days3219921992: Mar 21 – Apr 18, 35 sap days3519911991: Mar 3 – Apr 2, 38 sap days38
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Balsam Lake. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Polk County in the Census of Agriculture

USDA counts maple operations every five years. In Polk County the 2022 Census found 47 farms making syrup (+4% since 2017), with taps +96% and syrup output +503% over the same five years. That works out to about 0.73 gallons of syrup per tap in 2022 (0.24 in 2017). Among the 385 counties in this atlas, Polk County ranks 53 by taps.

Polk County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
20224754,93040,2240.73
20174527,9686,6730.24

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 Balsam Lake (1,152ft), 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

Polk County sugaring questions

When should I tap maple trees in Polk County, Wisconsin?
In a typical year the sap starts running around March 16 near Balsam Lake and the season winds down around April 10. 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 2.
How much maple syrup does Polk County produce?
The 2022 Census of Agriculture counted 47 maple operations in Polk County with 54,930 taps producing 40,224 gallons of syrup, ranking 9 of 60 Wisconsin's counties with published tap counts.
How many sap days does Polk County get in a season?
On average 33.4 freeze-thaw sap days from December through May at Balsam Lake, of which about 9.3 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2002 (50 sap days); the leanest was 2014 (19).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Balsam 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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