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Iowa · county maple atlas

Maple sugaring in Clayton County, Iowa

Clayton County had 8 maple operations in the 2022 Census (tap totals withheld). Around Elkader, sap usually runs from March 3 to April 3. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 148 days until the usual start.
Sap starts
Mar 3
weather estimate
Season ends
Apr 3
about 4 weeks
Sap days / season
42
1991–2026 average
Taps, 2022
withheld
8 farms

Sap-flow outlook at Elkader right now

Full Iowa forecast →

Forecast for Elkader, IA

Updated Oct 6, 9:06 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Clayton County's season usually opens around March 3, which is 148 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    54° / 74°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    49° / 67°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    46° / 70°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    55° / 76°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    60° / 77°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    57° / 68°
    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 Elkader

Freeze-thaw weather at Elkader peaks in the weeks of Feb 23 to Apr 6, which hold about 51% of a season's sap days. March is the busiest month. Note: USDA publishes no season dates for Iowa, so the typical dates here are the raw weather signal. In neighboring states with USDA records, producers reported their seasons running one to three weeks later than this rule.
Typical season: Mar 3 – Apr 30246Week of Dec 1: 1.8 sap days on averageWeek of Dec 8: 2.1 sap days on averageWeek of Dec 15: 1.6 sap days on averageWeek of Dec 22: 1.4 sap days on averageWeek of Dec 29: 0.9 sap days on averageWeek of Jan 5: 1.3 sap days on averageWeek of Jan 12: 0.8 sap days on averageWeek of Jan 19: 0.6 sap days on averageWeek of Jan 26: 1.2 sap days on averageWeek of Feb 2: 1.3 sap days on averageWeek of Feb 9: 1.6 sap days on averageWeek of Feb 16: 2.1 sap days on averageWeek of Feb 23: 2.3 sap days on averageWeek of Mar 2: 2.7 sap days on averageWeek of Mar 9: 3.3 sap days on averageWeek of Mar 16: 3.9 sap days on averageWeek of Mar 23: 3.7 sap days on averageWeek of Mar 30: 3.1 sap days on averageWeek of Apr 6: 2.4 sap days on averageWeek of Apr 13: 1.8 sap days on averageWeek of Apr 20: 1.1 sap days on averageWeek of Apr 27: 0.6 sap days on averageWeek of May 4: 0.2 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 3
Average number of freeze-thaw sap days in each week of the season at Elkader, 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 3; the middle half of seasons fell between Feb 24 and Mar 7. Earliest Feb 7 (2024), latest Mar 23 (2018).
Closing signal
Median Apr 3; middle half between Mar 27 and Apr 8. Earliest Mar 11 (2012), latest Apr 25 (2013).
Sap days by month
Dec17%Jan10%Feb17%Mar36%Apr18%May1%

36 seasons of sap weather

Clayton County seasons, 1991–2026

The best sap year at Elkader was 2002 with 72 freeze-thaw days; the leanest was 2010 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: Feb 16 – Mar 23, 42 sap days4220252025: Feb 21 – Mar 26, 52 sap days5220242024: Feb 7 – Mar 14, 63 sap days6320232023: Mar 7 – Apr 8, 52 sap days5220222022: Mar 9 – Apr 10, 50 sap days5020212021: Feb 28 – Apr 3, 45 sap days4520202020: Mar 3 – Apr 6, 57 sap days5720192019: Mar 5 – Apr 4, 38 sap days3820182018: Mar 23 – Apr 21, 60 sap days6020172017: Feb 21 – Mar 23, 33 sap days3320162016: Feb 20 – Mar 27, 44 sap days4420152015: Mar 2 – Apr 4, 32 sap days3220142014: Mar 16 – Apr 19, 36 sap days3620132013: Mar 22 – Apr 25, 41 sap days4120122012: Feb 12 – Mar 11, 48 sap days4820112011: Mar 7 – Apr 8, 36 sap days3620102010: Mar 3 – Mar 30, 19 sap days1920092009: Mar 4 – Apr 8, 42 sap days4220082008: Mar 16 – Apr 16, 25 sap days2520072007: Feb 21 – Mar 21, 42 sap days4220062006: Mar 4 – Apr 8, 55 sap days5520052005: Mar 1 – Mar 28, 49 sap days4920042004: Feb 25 – Apr 1, 44 sap days4420032003: Feb 25 – Mar 31, 37 sap days3720022002: Mar 7 – Apr 7, 72 sap days7220012001: Mar 10 – Apr 2, 25 sap days2520002000: Feb 28 – Mar 16, 46 sap days4619991999: Feb 26 – Mar 27, 41 sap days4119981998: Feb 22 – Mar 25, 22 sap days2219971997: Mar 1 – Apr 1, 35 sap days3519961996: Mar 13 – Apr 17, 49 sap days4919951995: Feb 22 – Mar 25, 28 sap days2819941994: Mar 7 – Apr 8, 41 sap days4119931993: Mar 18 – Apr 22, 31 sap days3119921992: Mar 3 – Apr 6, 47 sap days4719911991: Mar 1 – Apr 1, 32 sap days32
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Elkader. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Clayton County in the Census of Agriculture

USDA counts maple operations every five years. In Clayton County the 2022 Census found 8 farms making syrup (+33% since 2017).

Clayton County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
20228withheldwithheld—
20176withheldwithheld—

“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 Elkader (896ft), 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. 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 — Iowa, 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

Clayton County sugaring questions

When should I tap maple trees in Clayton County, Iowa?
In a typical year the sap starts running around March 3 near Elkader and the season winds down around April 3. 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 23.
How much maple syrup does Clayton County produce?
The 2022 Census of Agriculture counted 8 maple operations in Clayton County; USDA withheld the county's tap and gallon totals to avoid disclosing individual farms.
How many sap days does Clayton County get in a season?
On average 42 freeze-thaw sap days from December through May at Elkader, 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 (72 sap days); the leanest was 2010 (19).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Elkader (PRISM 4-km grid), scored with the same freeze-thaw rule as our live forecast, then calibrated against USDA's reported season dates for Iowa. 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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