When to tap maple trees in Iowa
- Opens
- —
- mid-to-late February
- Closes
- —
- March, once buds begin to break
County by county
When the sap runs across Iowa
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Typical opening date of the sap season, week by week across this state’s range
- Feb 20–22
- Feb 23–Mar 1
- Mar 2–4
- fewer than 5 maple farms
6 places with an atlas page. Typical season opening, earliest: Johnson County, IA, Feb 20; Dubuque County, IA, Feb 26; Hardin County, IA, Feb 27; latest: Winneshiek County, IA, Mar 4; Floyd County, IA, Mar 4; Clayton County, IA, Mar 3. Most sap days a season: Clayton County, IA, 42; Johnson County, IA, 40; Hardin County, IA, 39. Maple taps in the 2022 Census of Agriculture, on a five-step scale shared by both countries: under 1,000, 1,000–5,000, 5,000–20,000, 20,000–100,000, 100,000+; the most: Winneshiek County, IA (2,314), Johnson County, IA (370), Floyd County, IA (242), Hardin County, IA (50). Maple farms in the same census, in five steps: under 10, 10–20, 20–50, 50–100, 100+; the most: Johnson County, IA (9), Clayton County, IA (8), Dubuque County, IA (8). Syrup made, in US gallons: Winneshiek County, IA (888 gal), Johnson County, IA (47 gal), Floyd County, IA (27 gal). Tappable maples (FIA estimates of sugar maples 10 in and up on forest land, US counties only): under 1 million, 1–2 million, 2–5 million, 5–10 million, 10 million+; the most: Clayton County, IA (about 1.1 million ± 46%). 3 counties' estimates are too uncertain to show (sampling error over 50%). 2 counties have none tallied on the inventory plots (not a zero). Each shaded place links to its page; every state and province page lists its places in a table.
Sap-flow outlook right now
Full Iowa forecast →Forecast for Decorah
Updated Nov 10, 3:12 AM EST
3 sap days in the next 7
freeze thaw 32°F
- TueNov 1037° / 61°No refreeze forecast
- WedNov 1141° / 53°
0h below · 24h above
No refreeze forecast - ThuNov 1232° / 43°
1h below · 21h above
No refreeze forecast - FriNov 1325° / 41°
15h below · 9h above
Classic sap day - SatNov 1422° / 45°
12h below · 10h above
Classic sap day - SunNov 1528° / 48°
8h below · 16h above
Classic sap day - MonNov 1635° / 52°Run tapering
Data: National Weather Service. Verdicts use freeze-thaw thresholds from maple field research; your woods may run a little differently.
Timing your taps
How to know it's time in Iowa
Sap runs on a temperature swing, not a date. A night below freezing loads the tree; a day above freezing pushes sap out of the taphole. Field research treats a low under about 30°F followed by a high over about 37°F as a real freeze-thaw day, and big runs almost always come on days like that.
So watch the 10-day forecast. When you see a string of nights in the 20s and afternoons in the 40s, get your taps in a day or two ahead. South-facing slopes warm first and usually run earlier.
No NASS season data for Iowa. ISU Extension (2026): sap collection typically runs mid-February through early March. An older ISU page (reviewed 2019): collection usually begins in late February or early March and lasts about three weeks. Stop when buds break and nights stay warm.
Seasons are shifting. Cornell researchers found that start dates for tapping maples in the Northeast are about a week earlier than in 1970, and projected they could arrive about a month earlier by 2100 — e.g., around Feb 1 instead of Mar 1 in Montpelier, Vermont (Skinner, DeGaetano & Chabot, Climatic Change, 2010).
Where Iowa's sugaring happens
- DecorahISU says Iowa's commercial producers are in the northeast; Chickasaw, Winneshiek and Fayette counties report 29% of Iowa's taps, and Winneshiek County (Decorah) the most syrup (2022 Census of Agriculture).
FAQ
Iowa tapping questions
- When is maple syrup season in Iowa?
- Usually from mid-to-late February to March, once buds begin to break. The exact start moves by weeks from year to year with the weather.
- When should I tap my trees in Iowa?
- Tap just before the first good run: when the forecast shows nights below freezing and days climbing to around 40°F. Tapholes dry up within 6 to 10 weeks, so tapping far too early can cost you the late runs.
LuckySap · free on iPhone & Android
Get a heads-up when Iowa's sap will run
LuckySap checks the forecast for your trees and can ping you the night before a strong sap day, then keeps every collection and boil in one season log. Free on iPhone and Android.
