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Michigan · county maple atlas

Maple sugaring in Washtenaw County, Michigan

Washtenaw County had 13 maple operations and 6,370 taps in the 2022 Census. Around Ann Arbor, sap usually runs from February 19 to March 27. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 136 days until the usual start.
Sap starts
Feb 19
typical year
Season ends
Mar 27
about 5 weeks
Sap days / season
41.6
1991–2026 average
Taps, 2022
6,370
#30 of 66 in MI

Sap-flow outlook at Ann Arbor right now

Full Michigan forecast →

Forecast for Ann Arbor, MI

Updated Oct 6, 9:49 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Washtenaw County's season usually opens around February 19, which is 136 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    51° / 73°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    49° / 65°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    43° / 66°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    45° / 70°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    52° / 74°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    53° / 72°
    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 Ann Arbor

Freeze-thaw weather at Ann Arbor peaks in the weeks of Feb 16 to Apr 6, which hold about 53% of a season's sap days. March is the busiest month.
Typical season: Feb 19 – Mar 270246Week of Dec 1: 2.1 sap days on averageWeek of Dec 8: 2.1 sap days on averageWeek of Dec 15: 1.8 sap days on averageWeek of Dec 22: 1.7 sap days on averageWeek of Dec 29: 1.1 sap days on averageWeek of Jan 5: 1.4 sap days on averageWeek of Jan 12: 1.1 sap days on averageWeek of Jan 19: 0.9 sap days on averageWeek of Jan 26: 1.1 sap days on averageWeek of Feb 2: 1.8 sap days on averageWeek of Feb 9: 1.6 sap days on averageWeek of Feb 16: 2.3 sap days on averageWeek of Feb 23: 2.2 sap days on averageWeek of Mar 2: 3.2 sap days on averageWeek of Mar 9: 3.2 sap days on averageWeek of Mar 16: 3.5 sap days on averageWeek of Mar 23: 3.2 sap days on averageWeek of Mar 30: 2.5 sap days on averageWeek of Apr 6: 2.2 sap days on averageWeek of Apr 13: 1.1 sap days on averageWeek of Apr 20: 0.8 sap days on averageWeek of Apr 27: 0.4 sap days on averageWeek of May 4: 0.1 sap days on averageWeek of May 11: 0.1 sap days on averageWeek of May 18: 0.0 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Feb 19
Average number of freeze-thaw sap days in each week of the season at Ann Arbor, 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 23; the middle half of seasons fell between Feb 18 and Mar 2. Earliest Jan 25 (2017), latest Mar 10 (2014).
Closing signal
Median Mar 30; middle half between Mar 22 and Apr 4. Earliest Feb 28 (2017), latest Apr 11 (2018).
Sap days by month
Dec20%Jan12%Feb19%Mar34%Apr14%May1%

36 seasons of sap weather

Washtenaw County seasons, 1991–2026

The best sap year at Ann Arbor was 2018 with 60 freeze-thaw days; the leanest was 1993 with 30. 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 12 – Mar 19, 37 sap days3720252025: Feb 20 – Mar 27, 40 sap days4020242024: Feb 3 – Mar 3, 44 sap days4420232023: Feb 16 – Mar 21, 52 sap days5220222022: Mar 1 – Apr 3, 47 sap days4720212021: Feb 18 – Mar 22, 44 sap days4420202020: Feb 21 – Mar 26, 55 sap days5520192019: Mar 3 – Apr 2, 41 sap days4120182018: Mar 8 – Apr 11, 60 sap days6020172017: Jan 25 – Feb 28, 33 sap days3320162016: Feb 9 – Mar 13, 53 sap days5320152015: Mar 7 – Apr 6, 31 sap days3120142014: Mar 10 – Apr 7, 30 sap days3020132013: Mar 9 – Apr 6, 51 sap days5120122012: Feb 9 – Mar 12, 59 sap days5920112011: Mar 5 – Apr 6, 30 sap days3020102010: Feb 23 – Mar 30, 36 sap days3620092009: Feb 23 – Mar 30, 41 sap days4120082008: Mar 5 – Apr 6, 40 sap days4020072007: Feb 20 – Mar 22, 39 sap days3920062006: Feb 22 – Mar 29, 47 sap days4720052005: Mar 1 – Mar 29, 32 sap days3220042004: Feb 23 – Mar 25, 38 sap days3820032003: Feb 26 – Apr 1, 32 sap days3220022002: Feb 24 – Mar 31, 50 sap days5020012001: Mar 5 – Apr 5, 31 sap days3120002000: Feb 3 – Mar 7, 42 sap days4219991999: Feb 26 – Mar 30, 47 sap days4719981998: Feb 18 – Mar 25, 42 sap days4219971997: Feb 22 – Mar 25, 40 sap days4019961996: Feb 28 – Apr 3, 40 sap days4019951995: Feb 15 – Mar 19, 40 sap days4019941994: Feb 28 – Apr 4, 39 sap days3919931993: Mar 8 – Apr 4, 30 sap days3019921992: Mar 2 – Apr 6, 43 sap days4319911991: Feb 18 – Mar 20, 42 sap days42
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Ann Arbor. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Washtenaw County in the Census of Agriculture

USDA counts maple operations every five years. In Washtenaw County the 2022 Census found 13 farms making syrup (-50% since 2017), with taps +70% and syrup output +141% over the same five years. That works out to about 0.27 gallons of syrup per tap in 2022 (0.19 in 2017). Among the 385 counties in this atlas, Washtenaw County ranks 171 by taps.

Washtenaw County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
2022136,3701,6900.27
2017263,7567020.19

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 Ann Arbor (827ft), 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 Michigan'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 — Michigan, 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

Washtenaw County sugaring questions

When should I tap maple trees in Washtenaw County, Michigan?
In a typical year the sap starts running around February 19 near Ann Arbor and the season winds down around March 27. 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 25 and as late as Mar 10.
How much maple syrup does Washtenaw County produce?
The 2022 Census of Agriculture counted 13 maple operations in Washtenaw County with 6,370 taps producing 1,690 gallons of syrup, ranking 30 of 66 Michigan's counties with published tap counts.
How many sap days does Washtenaw County get in a season?
On average 41.6 freeze-thaw sap days from December through May at Ann Arbor, of which about 15.2 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2018 (60 sap days); the leanest was 1993 (30).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Ann Arbor (PRISM 4-km grid), scored with the same freeze-thaw rule as our live forecast, then calibrated against USDA's reported season dates for Michigan. 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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