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Wisconsin · county maple atlas

Maple sugaring in Iowa County, Wisconsin

Iowa County had 9 maple operations and 336 taps in the 2022 Census. Around Dodgeville, sap usually runs from March 9 to April 2. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 154 days until the usual start.
Sap starts
Mar 9
typical year
Season ends
Apr 2
about 3 weeks
Sap days / season
35.6
1991–2026 average
Taps, 2022
336
#50 of 60 in WI

Sap-flow outlook at Dodgeville right now

Full Wisconsin forecast →

Forecast for Dodgeville, WI

Updated Oct 6, 10:31 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Iowa County's season usually opens around March 9, which is 154 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    54° / 70°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    48° / 65°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    45° / 67°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    53° / 74°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    59° / 75°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    57° / 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 Dodgeville

Freeze-thaw weather at Dodgeville peaks in the weeks of Mar 2 to Apr 6, which hold about 48% of a season's sap days. March is the busiest month.
Typical season: Mar 9 – Apr 20246Week of Dec 1: 1.5 sap days on averageWeek of Dec 8: 1.6 sap days on averageWeek of Dec 15: 1.2 sap days on averageWeek of Dec 22: 1.0 sap days on averageWeek of Dec 29: 0.8 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: 0.8 sap days on averageWeek of Feb 2: 1.3 sap days on averageWeek of Feb 9: 1.4 sap days on averageWeek of Feb 16: 1.8 sap days on averageWeek of Feb 23: 2.0 sap days on averageWeek of Mar 2: 2.6 sap days on averageWeek of Mar 9: 2.9 sap days on averageWeek of Mar 16: 3.5 sap days on averageWeek of Mar 23: 3.3 sap days on averageWeek of Mar 30: 2.8 sap days on averageWeek of Apr 6: 2.2 sap days on averageWeek of Apr 13: 1.6 sap days on averageWeek of Apr 20: 0.7 sap days on averageWeek of Apr 27: 0.4 sap days on averageWeek of May 4: 0.2 sap days on averageWeek of May 11: 0.0 sap days on averageWeek of May 18: 0.0 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 9
Average number of freeze-thaw sap days in each week of the season at Dodgeville, 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 6; the middle half of seasons fell between Feb 28 and Mar 10. Earliest Feb 7 (2024), latest Mar 22 (2013).
Closing signal
Median Apr 5; middle half between Mar 27 and Apr 10. Earliest Mar 11 (2012), latest Apr 22 (1993).
Sap days by month
Dec16%Jan9%Feb18%Mar38%Apr18%May1%

36 seasons of sap weather

Iowa County seasons, 1991–2026

The best sap year at Dodgeville was 2002 with 51 freeze-thaw days; the leanest was 2010 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: Feb 16 – Mar 23, 41 sap days4120252025: Feb 21 – Mar 27, 41 sap days4120242024: Feb 7 – Mar 12, 46 sap days4620232023: Mar 8 – Apr 7, 46 sap days4620222022: Mar 9 – Apr 10, 44 sap days4420212021: Feb 28 – Apr 3, 36 sap days3620202020: Mar 4 – Apr 6, 51 sap days5120192019: Mar 5 – Apr 4, 36 sap days3620182018: Mar 21 – Apr 20, 49 sap days4920172017: Feb 19 – Mar 23, 24 sap days2420162016: Feb 18 – Mar 23, 30 sap days3020152015: Mar 7 – Apr 4, 22 sap days2220142014: Mar 16 – Apr 18, 29 sap days2920132013: Mar 22 – Apr 21, 27 sap days2720122012: Feb 12 – Mar 11, 39 sap days3920112011: Mar 8 – Apr 6, 27 sap days2720102010: Feb 28 – Mar 30, 22 sap days2220092009: Mar 6 – Apr 10, 36 sap days3620082008: Mar 16 – Apr 16, 24 sap days2420072007: Feb 21 – Mar 21, 34 sap days3420062006: Mar 7 – Apr 10, 42 sap days4220052005: Mar 4 – Mar 29, 38 sap days3820042004: Mar 1 – Apr 5, 41 sap days4120032003: Mar 6 – Apr 10, 35 sap days3520022002: Mar 7 – Apr 7, 51 sap days5120012001: Mar 10 – Apr 4, 25 sap days2520002000: Feb 28 – Mar 18, 39 sap days3919991999: Mar 13 – Mar 27, 35 sap days3519981998: Feb 23 – Mar 25, 25 sap days2519971997: Mar 11 – Apr 15, 32 sap days3219961996: Mar 16 – Apr 19, 42 sap days4219951995: Feb 27 – Apr 3, 31 sap days3119941994: Mar 10 – Apr 7, 39 sap days3919931993: Mar 20 – Apr 22, 30 sap days3019921992: Mar 7 – Apr 9, 40 sap days4019911991: Mar 2 – Apr 2, 34 sap days34
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Dodgeville. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Iowa County in the Census of Agriculture

USDA counts maple operations every five years. In Iowa County the 2022 Census found 9 farms making syrup (+29% since 2017), with taps -24% and syrup output +37% over the same five years. That works out to about 0.19 gallons of syrup per tap in 2022 (0.10 in 2017). Among the 385 counties in this atlas, Iowa County ranks 327 by taps.

Iowa County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
20229336630.19
20177440460.10

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 Dodgeville (1,198ft), 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

Iowa County sugaring questions

When should I tap maple trees in Iowa County, Wisconsin?
In a typical year the sap starts running around March 9 near Dodgeville and the season winds down around April 2. 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 7 and as late as Mar 22.
How much maple syrup does Iowa County produce?
The 2022 Census of Agriculture counted 9 maple operations in Iowa County with 336 taps producing 63 gallons of syrup, ranking 50 of 60 Wisconsin's counties with published tap counts.
How many sap days does Iowa County get in a season?
On average 35.6 freeze-thaw sap days from December through May at Dodgeville, of which about 11.8 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2002 (51 sap days); the leanest was 2010 (22).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Dodgeville (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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