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Michigan · county maple atlas

Maple sugaring in Alger County, Michigan

Alger County had 10 maple operations and 18,500 taps in the 2022 Census. Around Munising, sap usually runs from March 25 to April 24. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 170 days until the usual start.
Sap starts
Mar 25
typical year
Season ends
Apr 24
about 4 weeks
Sap days / season
28.4
1991–2026 average
Taps, 2022
18,500
#10 of 66 in MI

Sap-flow outlook at Munising right now

Full Michigan forecast →

Forecast for Munising, MI

Updated Oct 6, 10:24 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. Alger County's season usually opens around March 25, which is 170 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    49° / 64°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    41° / 57°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    35° / 59°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    42° / 67°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    54° / 71°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    47° / 61°
    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 Munising

Freeze-thaw weather at Munising peaks in the weeks of Mar 9 to Apr 27, which hold about 61% of a season's sap days. April is the busiest month.
Typical season: Mar 25 – Apr 240246Week of Dec 1: 1.1 sap days on averageWeek of Dec 8: 1.2 sap days on averageWeek of Dec 15: 0.7 sap days on averageWeek of Dec 22: 0.6 sap days on averageWeek of Dec 29: 0.2 sap days on averageWeek of Jan 5: 0.5 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: 0.3 sap days on averageWeek of Feb 2: 0.6 sap days on averageWeek of Feb 9: 0.6 sap days on averageWeek of Feb 16: 0.8 sap days on averageWeek of Feb 23: 0.9 sap days on averageWeek of Mar 2: 1.4 sap days on averageWeek of Mar 9: 1.8 sap days on averageWeek of Mar 16: 1.8 sap days on averageWeek of Mar 23: 2.4 sap days on averageWeek of Mar 30: 2.5 sap days on averageWeek of Apr 6: 2.4 sap days on averageWeek of Apr 13: 2.2 sap days on averageWeek of Apr 20: 2.5 sap days on averageWeek of Apr 27: 1.7 sap days on averageWeek of May 4: 0.9 sap days on averageWeek of May 11: 0.6 sap days on averageWeek of May 18: 0.3 sap days on averageWeek of May 25: 0.2 sap days on averageDecJanFebMarAprMaytaps in ~Mar 25
Average number of freeze-thaw sap days in each week of the season at Munising, 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 29; the middle half of seasons fell between Mar 20 and Apr 1. Earliest Feb 18 (2012), latest Apr 13 (2020).
Closing signal
Median Apr 27; middle half between Apr 19 and May 3. Earliest Mar 18 (2012), latest May 14 (1996).
Sap days by month
Dec13%Jan4%Feb10%Mar29%Apr35%May8%

36 seasons of sap weather

Alger County seasons, 1991–2026

The best sap year at Munising was 1994 with 41 freeze-thaw days; the leanest was 2006 with 20. 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 24 – Apr 22, 27 sap days2720252025: Mar 30 – Apr 30, 34 sap days3420242024: Mar 10 – Apr 8, 31 sap days3120232023: Mar 29 – Apr 19, 24 sap days2420222022: Apr 3 – May 5, 21 sap days2120212021: Mar 9 – Apr 4, 29 sap days2920202020: Apr 13 – May 14, 37 sap days3720192019: Apr 4 – May 8, 25 sap days2520182018: Apr 6 – May 11, 26 sap days2620172017: Mar 16 – Apr 18, 22 sap days2220162016: Mar 25 – Apr 24, 26 sap days2620152015: Mar 28 – May 1, 23 sap days2320142014: Apr 6 – May 6, 22 sap days2220132013: Apr 3 – Apr 26, 26 sap days2620122012: Feb 18 – Mar 18, 33 sap days3320112011: Mar 31 – May 4, 24 sap days2420102010: Mar 5 – Mar 30, 25 sap days2520092009: Mar 29 – Apr 29, 27 sap days2720082008: Mar 29 – May 2, 27 sap days2720072007: Mar 18 – Apr 20, 26 sap days2620062006: Mar 15 – Apr 18, 20 sap days2020052005: Mar 23 – Apr 15, 27 sap days2720042004: Apr 1 – Apr 29, 30 sap days3020032003: Mar 31 – May 4, 31 sap days3120022002: Mar 30 – Apr 27, 38 sap days3820012001: Mar 24 – Apr 28, 22 sap days2220002000: Mar 16 – Apr 18, 32 sap days3219991999: Mar 20 – Apr 24, 37 sap days3719981998: Mar 12 – Apr 11, 24 sap days2419971997: Apr 3 – May 4, 22 sap days2219961996: Apr 11 – May 14, 33 sap days3319951995: Mar 27 – Apr 24, 37 sap days3719941994: Mar 29 – May 2, 41 sap days4119931993: Apr 1 – Apr 27, 27 sap days2719921992: Mar 30 – Apr 29, 31 sap days3119911991: Mar 21 – Apr 24, 37 sap days37
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Munising. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

Alger County in the Census of Agriculture

USDA counts maple operations every five years. In Alger County the 2022 Census found 10 farms making syrup (+43% since 2017), with taps +0% and syrup output +30% over the same five years. That works out to about 0.26 gallons of syrup per tap in 2022 (0.20 in 2017). Among the 385 counties in this atlas, Alger County ranks 97 by taps.

Alger County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
20221018,5004,7830.26
2017718,4103,6780.20

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 Munising (787ft), 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

Alger County sugaring questions

When should I tap maple trees in Alger County, Michigan?
In a typical year the sap starts running around March 25 near Munising and the season winds down around April 24. 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 18 and as late as Apr 13.
How much maple syrup does Alger County produce?
The 2022 Census of Agriculture counted 10 maple operations in Alger County with 18,500 taps producing 4,783 gallons of syrup, ranking 10 of 66 Michigan's counties with published tap counts.
How many sap days does Alger County get in a season?
On average 28.4 freeze-thaw sap days from December through May at Munising, of which about 11.1 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 1994 (41 sap days); the leanest was 2006 (20).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Munising (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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