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Illinois · county maple atlas

Maple sugaring in LaSalle County, Illinois

LaSalle County had 5 maple operations and 95 taps in the 2022 Census, number 4 in Illinois. Around Ottawa, sap usually runs from February 18 to March 21. Here's the long-run pattern, 36 seasons of sap weather, and the outlook this week.
Too early to tapAbout 135 days until the usual start.
Sap starts
Feb 18
weather estimate
Season ends
Mar 21
about 4 weeks
Sap days / season
40
1991–2026 average
Taps, 2022
95
#4 of 26 in IL

Sap-flow outlook at Ottawa right now

Full Illinois forecast →

Forecast for Ottawa, IL

Updated Oct 6, 10:36 AM EDT

Off-season for now. Sap needs freezing nights, and none are in sight. LaSalle County's season usually opens around February 18, which is 135 days away.

No freeze-thaw days in the forecast

freeze thaw 32°F

  1. WedOct 7
    55° / 78°

    0h below · 24h above

    No refreeze forecast
  2. ThuOct 8
    50° / 71°

    0h below · 24h above

    No refreeze forecast
  3. FriOct 9
    46° / 74°

    0h below · 24h above

    No refreeze forecast
  4. SatOct 10
    53° / 80°

    0h below · 24h above

    No refreeze forecast
  5. SunOct 11
    58° / 80°

    0h below · 24h above

    No refreeze forecast
  6. MonOct 12
    59° / 78°
    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 Ottawa

Freeze-thaw weather at Ottawa peaks in the weeks of Feb 2 to Mar 30, which hold about 57% of a season's sap days. March is the busiest month. Note: USDA publishes no season dates for Illinois, 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 18 – Mar 210246Week of Dec 1: 2.1 sap days on averageWeek of Dec 8: 2.3 sap days on averageWeek of Dec 15: 2.2 sap days on averageWeek of Dec 22: 1.7 sap days on averageWeek of Dec 29: 1.4 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: 1.4 sap days on averageWeek of Feb 2: 2.0 sap days on averageWeek of Feb 9: 2.1 sap days on averageWeek of Feb 16: 2.4 sap days on averageWeek of Feb 23: 2.4 sap days on averageWeek of Mar 2: 3.0 sap days on averageWeek of Mar 9: 2.9 sap days on averageWeek of Mar 16: 3.2 sap days on averageWeek of Mar 23: 2.8 sap days on averageWeek of Mar 30: 2.0 sap days on averageWeek of Apr 6: 1.6 sap days on averageWeek of Apr 13: 0.9 sap days on averageWeek of Apr 20: 0.2 sap days on averageWeek of Apr 27: 0.1 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 18
Average number of freeze-thaw sap days in each week of the season at Ottawa, 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 18; the middle half of seasons fell between Feb 7 and Feb 23. Earliest Jan 23 (2017), latest Mar 7 (2014).
Closing signal
Median Mar 21; middle half between Mar 12 and Mar 28. Earliest Feb 27 (2017), latest Apr 6 (2014).
Sap days by month
Dec22%Jan13%Feb22%Mar32%Apr10%May0%

36 seasons of sap weather

LaSalle County seasons, 1991–2026

The best sap year at Ottawa was 2018 with 63 freeze-thaw days; the leanest was 2010 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: Feb 1 – Mar 3, 34 sap days3420252025: Feb 10 – Mar 17, 30 sap days3020242024: Jan 29 – Mar 4, 44 sap days4420232023: Feb 15 – Mar 21, 51 sap days5120222022: Feb 17 – Mar 14, 40 sap days4020212021: Feb 22 – Mar 21, 41 sap days4120202020: Feb 21 – Mar 26, 43 sap days4320192019: Feb 27 – Apr 2, 46 sap days4620182018: Feb 18 – Mar 25, 63 sap days6320172017: Jan 23 – Feb 27, 38 sap days3820162016: Feb 6 – Mar 7, 38 sap days3820152015: Feb 27 – Mar 29, 29 sap days2920142014: Mar 7 – Apr 6, 28 sap days2820132013: Mar 5 – Apr 5, 38 sap days3820122012: Feb 7 – Mar 12, 46 sap days4620112011: Feb 23 – Mar 30, 27 sap days2720102010: Feb 28 – Mar 27, 16 sap days1620092009: Feb 14 – Mar 21, 34 sap days3420082008: Feb 28 – Apr 4, 41 sap days4120072007: Feb 17 – Mar 19, 36 sap days3620062006: Feb 6 – Mar 8, 49 sap days4920052005: Feb 23 – Mar 29, 49 sap days4920042004: Feb 18 – Mar 24, 48 sap days4820032003: Feb 19 – Mar 15, 34 sap days3420022002: Feb 7 – Mar 13, 55 sap days5520012001: Mar 2 – Apr 2, 32 sap days3220002000: Jan 31 – Mar 6, 46 sap days4619991999: Feb 23 – Mar 28, 46 sap days4619981998: Jan 30 – Mar 6, 34 sap days3419971997: Feb 20 – Mar 24, 40 sap days4019961996: Feb 18 – Mar 25, 51 sap days5119951995: Feb 11 – Mar 10, 40 sap days4019941994: Feb 20 – Mar 25, 37 sap days3719931993: Mar 4 – Apr 5, 35 sap days3519921992: Jan 31 – Mar 2, 42 sap days4219911991: Feb 18 – Mar 16, 39 sap days39
Each bar runs from the season's opening signal to its closing signal, estimated from daily temperatures at Ottawa. Dashed lines mark the typical dates. The right column counts freeze-thaw sap days from December through May.

Maple production

LaSalle County in the Census of Agriculture

USDA counts maple operations every five years. In LaSalle 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 0.08 gallons of syrup per tap in 2022. Among the 385 counties in this atlas, LaSalle County ranks 364 by taps.

LaSalle County maple production, 2017 and 2022 (USDA Census of Agriculture)
Census yearFarmsTapsGallons of syrupGal / tap
202259580.08
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 Ottawa (541ft), 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 — Illinois, 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

LaSalle County sugaring questions

When should I tap maple trees in LaSalle County, Illinois?
In a typical year the sap starts running around February 18 near Ottawa and the season winds down around March 21. 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 23 and as late as Mar 7.
How much maple syrup does LaSalle County produce?
The 2022 Census of Agriculture counted 5 maple operations in LaSalle County with 95 taps producing 8 gallons of syrup, ranking 4 of 26 Illinois' counties with published tap counts.
How many sap days does LaSalle County get in a season?
On average 40 freeze-thaw sap days from December through May at Ottawa, of which about 15.3 are textbook days with a night in the 20s and a day in the 40s. The best season since 1991 was 2018 (63 sap days); the leanest was 2010 (16).
Where do these dates come from?
From 36 seasons of daily high and low temperatures at Ottawa (PRISM 4-km grid), scored with the same freeze-thaw rule as our live forecast, then calibrated against USDA's reported season dates for Illinois. 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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