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Minnesota · county maple atlas

Maple sugaring in St. Louis County, Minnesota

St. Louis County had 34 maple operations and 7,080 taps in the 2022 Census, number 3 in Minnesota. Around Duluth, sap usually runs from March 19 to April 15. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 164 days until the usual start.
Sap starts
Mar 19
typical year
Season ends
Apr 15
about 4 weeks
Sap days / season
26.3
1991–2026 average
Taps, 2022
7,080
#3 of 41 in MN

Sap-flow outlook at Duluth right now

Full Minnesota forecast →

Forecast for Duluth, MN

Updated Oct 6, 10:51 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. St. Louis County's season usually opens around March 19, which is 164 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    50° / 66°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    44° / 62°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    44° / 61°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    50° / 71°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    57° / 66°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    49° / 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 Duluth

Freeze-thaw weather at Duluth peaks in the weeks of Mar 9 to Apr 20, which hold about 59% of a season's sap days. April is the busiest month.
Typical season: Mar 19 – Apr 150246Week of Dec 1: 0.8 sap days on averageWeek of Dec 8: 0.8 sap days on averageWeek of Dec 15: 0.5 sap days on averageWeek of Dec 22: 0.4 sap days on averageWeek of Dec 29: 0.2 sap days on averageWeek of Jan 5: 0.3 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: 0.4 sap days on averageWeek of Feb 2: 0.8 sap days on averageWeek of Feb 9: 0.7 sap days on averageWeek of Feb 16: 0.9 sap days on averageWeek of Feb 23: 1.0 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: 1.9 sap days on averageWeek of Mar 23: 2.7 sap days on averageWeek of Mar 30: 2.6 sap days on averageWeek of Apr 6: 2.4 sap days on averageWeek of Apr 13: 1.9 sap days on averageWeek of Apr 20: 2.2 sap days on averageWeek of Apr 27: 1.3 sap days on averageWeek of May 4: 0.3 sap days on averageWeek of May 11: 0.3 sap days on averageWeek of May 18: 0.1 sap days on averageWeek of May 25: 0.0 sap days on averageDecJanFebMarAprMaytaps in ~Mar 19
Average number of freeze-thaw sap days in each week of the season at Duluth, 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 21 and Apr 2. Earliest Feb 21 (2012), latest Apr 14 (1996).
Closing signal
Median Apr 24; middle half between Apr 15 and May 1. Earliest Mar 28 (2012), latest May 14 (1996).
Sap days by month
Dec10%Jan5%Feb13%Mar33%Apr35%May5%

36 seasons of sap weather

St. Louis County seasons, 1991–2026

The best sap year at Duluth was 2024 with 42 freeze-thaw days; the leanest was 2001 with 16. 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 21, 40 sap days4020252025: Mar 24 – Apr 21, 36 sap days3620242024: Mar 12 – Apr 7, 42 sap days4220232023: Apr 3 – Apr 27, 27 sap days2720222022: Apr 6 – May 4, 23 sap days2320212021: Mar 13 – Apr 3, 31 sap days3120202020: Apr 2 – Apr 25, 35 sap days3520192019: Mar 30 – May 3, 29 sap days2920182018: Apr 1 – Apr 29, 30 sap days3020172017: Mar 12 – Apr 12, 23 sap days2320162016: Mar 29 – Apr 14, 19 sap days1920152015: Mar 12 – Apr 11, 23 sap days2320142014: Apr 8 – Apr 23, 17 sap days1720132013: Apr 10 – Apr 25, 20 sap days2020122012: Feb 21 – Mar 28, 26 sap days2620112011: Mar 29 – May 3, 24 sap days2420102010: Mar 6 – Apr 10, 19 sap days1920092009: Mar 28 – Apr 15, 19 sap days1920082008: Apr 2 – Apr 30, 23 sap days2320072007: Mar 21 – Apr 18, 23 sap days2320062006: Mar 18 – Apr 9, 21 sap days2120052005: Mar 15 – Apr 7, 24 sap days2420042004: Mar 29 – May 3, 37 sap days3720032003: Mar 30 – May 3, 24 sap days2420022002: Apr 7 – May 5, 35 sap days3520012001: Mar 27 – Apr 19, 16 sap days1620002000: Mar 23 – Apr 22, 31 sap days3119991999: Mar 23 – Apr 24, 33 sap days3319981998: Mar 23 – Apr 16, 20 sap days2019971997: Apr 2 – May 1, 20 sap days2019961996: Apr 14 – May 14, 27 sap days2719951995: Apr 5 – May 1, 24 sap days2419941994: Mar 20 – Apr 22, 31 sap days3119931993: Apr 1 – Apr 26, 25 sap days2519921992: Apr 3 – May 6, 25 sap days2519911991: Mar 22 – Apr 24, 25 sap days25
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Duluth. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

St. Louis County in the Census of Agriculture

USDA counts maple operations every five years. In St. Louis County the 2022 Census found 34 farms making syrup (+209% since 2017), with taps 0% and syrup output +54% over the same five years. That works out to about 0.20 gallons of syrup per tap in 2022 (0.13 in 2017). Among the 385 counties in this atlas, St. Louis County ranks 162 by taps.

St. Louis County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
2022347,0801,4050.20
2017117,0929140.13

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 Duluth (1,207ft), 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

St. Louis County sugaring questions

When should I tap maple trees in St. Louis County, Minnesota?
In a typical year the sap starts running around March 19 near Duluth and the season winds down around April 15. 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 21 and as late as Apr 14.
How much maple syrup does St. Louis County produce?
The 2022 Census of Agriculture counted 34 maple operations in St. Louis County with 7,080 taps producing 1,405 gallons of syrup, ranking 3 of 41 Minnesota's counties with published tap counts.
How many sap days does St. Louis County get in a season?
On average 26.3 freeze-thaw sap days from December through May at Duluth, of which about 10.4 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2024 (42 sap days); the leanest was 2001 (16).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Duluth (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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