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Minnesota · county maple atlas

Maple sugaring in Otter Tail County, Minnesota

Otter Tail County had 9 maple operations and 4,132 taps in the 2022 Census. Around Fergus Falls, sap usually runs from March 7 to April 6. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 152 days until the usual start.
Sap starts
Mar 7
typical year
Season ends
Apr 6
about 4 weeks
Sap days / season
26.9
1991–2026 average
Taps, 2022
4,132
#6 of 41 in MN

Sap-flow outlook at Fergus Falls right now

Full Minnesota forecast →

Forecast for Fergus Falls, MN

Updated Oct 6, 10:36 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Otter Tail County's season usually opens around March 7, which is 152 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    47° / 67°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    42° / 63°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    44° / 68°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    55° / 77°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    55° / 63°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    45° / 53°
    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 Fergus Falls

Freeze-thaw weather at Fergus Falls peaks in the weeks of Mar 9 to Apr 13, which hold about 53% of a season's sap days. March is the busiest month.
Typical season: Mar 7 – Apr 60246Week of Dec 1: 1.0 sap days on averageWeek of Dec 8: 1.2 sap days on averageWeek of Dec 15: 0.6 sap days on averageWeek of Dec 22: 0.7 sap days on averageWeek of Dec 29: 0.1 sap days on averageWeek of Jan 5: 0.4 sap days on averageWeek of Jan 12: 0.2 sap days on averageWeek of Jan 19: 0.1 sap days on averageWeek of Jan 26: 0.7 sap days on averageWeek of Feb 2: 0.8 sap days on averageWeek of Feb 9: 0.8 sap days on averageWeek of Feb 16: 1.0 sap days on averageWeek of Feb 23: 0.8 sap days on averageWeek of Mar 2: 1.3 sap days on averageWeek of Mar 9: 1.8 sap days on averageWeek of Mar 16: 2.6 sap days on averageWeek of Mar 23: 2.7 sap days on averageWeek of Mar 30: 2.5 sap days on averageWeek of Apr 6: 2.6 sap days on averageWeek of Apr 13: 2.0 sap days on averageWeek of Apr 20: 1.4 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: 0.0 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 7
Average number of freeze-thaw sap days in each week of the season at Fergus Falls, 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 17; the middle half of seasons fell between Mar 10 and Mar 24. Earliest Feb 16 (2012), latest Apr 6 (2013).
Closing signal
Median Apr 15; middle half between Apr 6 and Apr 22. Earliest Mar 14 (2012), latest May 4 (2013).
Sap days by month
Dec13%Jan5%Feb13%Mar34%Apr32%May3%

36 seasons of sap weather

Otter Tail County seasons, 1991–2026

The best sap year at Fergus Falls was 2021 with 49 freeze-thaw days; the leanest was 2001 with 10. 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 12 – Apr 11, 43 sap days4320252025: Mar 14 – Apr 16, 37 sap days3720242024: Mar 7 – Apr 6, 46 sap days4620232023: Apr 2 – Apr 26, 13 sap days1320222022: Apr 1 – Apr 28, 30 sap days3020212021: Mar 4 – Apr 4, 49 sap days4920202020: Mar 24 – Apr 23, 27 sap days2720192019: Mar 21 – Apr 15, 21 sap days2120182018: Mar 29 – Apr 28, 24 sap days2420172017: Mar 1 – Mar 29, 23 sap days2320162016: Mar 11 – Apr 14, 35 sap days3520152015: Mar 8 – Apr 10, 22 sap days2220142014: Mar 25 – Apr 22, 17 sap days1720132013: Apr 6 – May 4, 17 sap days1720122012: Feb 16 – Mar 14, 26 sap days2620112011: Mar 22 – Apr 21, 22 sap days2220102010: Mar 17 – Mar 29, 13 sap days1320092009: Mar 19 – Apr 12, 15 sap days1520082008: Mar 29 – May 1, 34 sap days3420072007: Mar 16 – Apr 14, 28 sap days2820062006: Mar 10 – Apr 9, 17 sap days1720052005: Mar 5 – Apr 1, 29 sap days2920042004: Mar 11 – Apr 15, 35 sap days3520032003: Mar 22 – Apr 9, 22 sap days2220022002: Mar 15 – Apr 19, 40 sap days4020012001: Apr 1 – Apr 23, 10 sap days1020002000: Feb 24 – Mar 30, 39 sap days3919991999: Mar 9 – Mar 26, 28 sap days2819981998: Mar 17 – Apr 3, 16 sap days1619971997: Mar 26 – Apr 18, 17 sap days1719961996: Mar 27 – May 1, 23 sap days2319951995: Mar 18 – Apr 22, 26 sap days2619941994: Mar 17 – Apr 11, 27 sap days2719931993: Mar 18 – Apr 21, 21 sap days2119921992: Mar 22 – Apr 24, 36 sap days3619911991: Mar 3 – Apr 1, 42 sap days42
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Fergus Falls. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Otter Tail County in the Census of Agriculture

USDA counts maple operations every five years. In Otter Tail County the 2022 Census found 9 farms making syrup (-53% since 2017), with taps +16% and syrup output +88% over the same five years. That works out to about 0.22 gallons of syrup per tap in 2022 (0.14 in 2017). Among the 385 counties in this atlas, Otter Tail County ranks 209 by taps.

Otter Tail County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
202294,1329110.22
2017193,5704840.14

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 Fergus Falls (1,217ft), 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 Minnesota's USDA record (3 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 — Minnesota, 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

Otter Tail County sugaring questions

When should I tap maple trees in Otter Tail County, Minnesota?
In a typical year the sap starts running around March 7 near Fergus Falls and the season winds down around April 6. 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 16 and as late as Apr 6.
How much maple syrup does Otter Tail County produce?
The 2022 Census of Agriculture counted 9 maple operations in Otter Tail County with 4,132 taps producing 911 gallons of syrup, ranking 6 of 41 Minnesota's counties with published tap counts.
How many sap days does Otter Tail County get in a season?
On average 26.9 freeze-thaw sap days from December through May at Fergus Falls, of which about 8.6 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2021 (49 sap days); the leanest was 2001 (10).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Fergus Falls (PRISM 4-km grid), scored with the same freeze-thaw rule as our live forecast, then calibrated against USDA's reported season dates for Minnesota. 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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