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Iowa · county maple atlas

Maple sugaring in Hardin County, Iowa

Hardin County had 5 maple operations and 50 taps in the 2022 Census. Around Eldora, sap usually runs from February 27 to March 31. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 144 days until the usual start.
Sap starts
Feb 27
weather estimate
Season ends
Mar 31
about 5 weeks
Sap days / season
38.5
1991–2026 average
Taps, 2022
50
#9 of 32 in IA

Sap-flow outlook at Eldora right now

Full Iowa forecast →

Forecast for Eldora, IA

Updated Oct 6, 6:51 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Hardin County's season usually opens around February 27, which is 144 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    55° / 75°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    50° / 68°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    48° / 72°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    58° / 78°

    0h below · 24h above

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

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    58° / 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 Eldora

Freeze-thaw weather at Eldora peaks in the weeks of Mar 2 to Mar 30, which hold about 37% 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: Feb 27 – Mar 310246Week of Dec 1: 1.9 sap days on averageWeek of Dec 8: 2.2 sap days on averageWeek of Dec 15: 1.6 sap days on averageWeek of Dec 22: 1.5 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: 1.1 sap days on averageWeek of Jan 19: 0.8 sap days on averageWeek of Jan 26: 1.2 sap days on averageWeek of Feb 2: 1.4 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: 2.1 sap days on averageWeek of Mar 2: 2.4 sap days on averageWeek of Mar 9: 2.8 sap days on averageWeek of Mar 16: 3.6 sap days on averageWeek of Mar 23: 2.9 sap days on averageWeek of Mar 30: 2.6 sap days on averageWeek of Apr 6: 2.1 sap days on averageWeek of Apr 13: 1.4 sap days on averageWeek of Apr 20: 0.8 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: 0.0 sap days on averageWeek of May 18: 0.0 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Feb 27
Average number of freeze-thaw sap days in each week of the season at Eldora, 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 Feb 27; the middle half of seasons fell between Feb 21 and Mar 7. Earliest Jan 31 (2024), latest Mar 22 (2013).
Closing signal
Median Mar 31; middle half between Mar 23 and Apr 7. Earliest Mar 5 (2000), latest Apr 25 (2013).
Sap days by month
Dec20%Jan12%Feb19%Mar33%Apr16%May0%

36 seasons of sap weather

Hardin County seasons, 1991–2026

The best sap year at Eldora was 2002 with 60 freeze-thaw days; the leanest was 2010 with 13. 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 13 – Mar 19, 38 sap days3820252025: Feb 11 – Mar 17, 40 sap days4020242024: Jan 31 – Mar 7, 52 sap days5220232023: Mar 6 – Apr 7, 52 sap days5220222022: Mar 7 – Apr 10, 51 sap days5120212021: Feb 22 – Mar 21, 42 sap days4220202020: Feb 27 – Apr 1, 57 sap days5720192019: Mar 4 – Apr 4, 41 sap days4120182018: Mar 21 – Apr 21, 54 sap days5420172017: Feb 17 – Mar 23, 33 sap days3320162016: Feb 15 – Mar 22, 40 sap days4020152015: Feb 24 – Mar 29, 27 sap days2720142014: Mar 12 – Apr 16, 34 sap days3420132013: Mar 22 – Apr 25, 39 sap days3920122012: Feb 11 – Mar 11, 44 sap days4420112011: Mar 5 – Apr 6, 32 sap days3220102010: Mar 20 – Mar 30, 13 sap days1320092009: Feb 23 – Mar 30, 28 sap days2820082008: Mar 14 – Apr 16, 26 sap days2620072007: Feb 20 – Mar 21, 43 sap days4320062006: Mar 1 – Apr 5, 49 sap days4920052005: Feb 27 – Apr 2, 47 sap days4720042004: Feb 21 – Mar 24, 40 sap days4020032003: Feb 21 – Mar 14, 40 sap days4020022002: Mar 4 – Apr 7, 60 sap days6020012001: Mar 14 – Apr 2, 17 sap days1720002000: Feb 2 – Mar 5, 41 sap days4119991999: Feb 25 – Mar 27, 39 sap days3919981998: Mar 20 – Mar 25, 18 sap days1819971997: Feb 27 – Apr 1, 37 sap days3719961996: Mar 8 – Apr 11, 45 sap days4519951995: Feb 21 – Mar 24, 25 sap days2519941994: Mar 4 – Apr 8, 36 sap days3619931993: Mar 17 – Apr 21, 20 sap days2019921992: Feb 19 – Mar 25, 48 sap days4819911991: Feb 26 – Apr 1, 38 sap days38
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Eldora. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Hardin County in the Census of Agriculture

USDA counts maple operations every five years. In Hardin County the 2022 Census found 5 farms making syrup, with taps null and syrup output null over the same five years. That works out to about 0.22 gallons of syrup per tap in 2022. Among the 385 counties in this atlas, Hardin County ranks 369 by taps.

Hardin County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
2022550110.22
2017000—

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 Eldora (1,056ft), 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

Hardin County sugaring questions

When should I tap maple trees in Hardin County, Iowa?
In a typical year the sap starts running around February 27 near Eldora and the season winds down around March 31. 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 Jan 31 and as late as Mar 22.
How much maple syrup does Hardin County produce?
The 2022 Census of Agriculture counted 5 maple operations in Hardin County with 50 taps producing 11 gallons of syrup, ranking 9 of 32 Iowa's counties with published tap counts.
How many sap days does Hardin County get in a season?
On average 38.5 freeze-thaw sap days from December through May at Eldora, of which about 12.3 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2002 (60 sap days); the leanest was 2010 (13).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Eldora (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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