U.S. Frost Dates by Weather Station

NOAA station USC00133517 · Iowa

Frost Dates near Guttenberg, IA

NOAA weather station Guttenberg Lock and Dam 10 (USC00133517), Iowa · elevation 618 ft (188 m) · hardiness zone 5a*

Guttenberg is the nearest town to the station (0.2 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 6only 1 spring in 10 still has a frost later
  • Typical last frostApril 2150% chance of a frost after it
  • Typical first fall frostOctober 1850% chance of a frost before it
  • Frost-free season178 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season near Guttenberg, IASpring: a frost after April 7 in 9 years out of 10, after April 21 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 18 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 178 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 21First frost ~Oct 18Frost season near Guttenberg, IASpring: a frost after April 7 in 9 years out of 10, after April 21 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 18 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 178 days.JFMAMJJASONDLast frost ~Apr 21First frost ~Oct 18
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 6October 4
50% (typical)April 21October 18
90% (likely)April 7October 30
Frost-free season (32°F, 50% chance)
178 days
Hard frost (28°F), last in spring, 50% chance after
April 9
Hard frost (28°F), first in fall, 50% chance before
October 27

The last 15 years (2006–2020 normals)

Typical last frost April 22 (1 day later than the 30-year normal), typical first fall frost October 20 (2 days later). Frost-free season 180 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring near Guttenberg: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 6, 20% May 2, 30% April 30, 40% April 25, 50% April 21, 60% April 19, 70% April 15, 80% April 11, 90% April 7. Observed last spring frost in recent years: 2021 April 22, 2022 April 27, 2023 April 25, 2024 April 22, 2025 April 9, 2026 April 21.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 6Apr 21Apr 72021: April 222022: April 272023: April 252024: April 222025: April 92026: April 21Fall near Guttenberg: chance of a frost before this dateFall, chance of a frost before the date: 10% October 4, 20% October 9, 30% October 12, 40% October 15, 50% October 18, 60% October 20, 70% October 23, 80% October 26, 90% October 30. Observed first fall frost in recent years: 2021 November 1, 2022 October 9, 2023 October 30, 2024 October 16, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 4Oct 18Oct 302021: November 12022: October 92023: October 302024: October 162025: October 24
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021April 22November 1
2022April 27October 9
2023April 25October 30
2024April 22October 16
2025April 9October 24
2026April 21season not over yet

What these dates mean

Setting out tender crops on the early spring date, April 7, carries a 90 % chance of a frost later that season, so it is a gamble for gardeners in the Guttenberg area.

The 50 % date is April 21 in spring and October 18 in fall; each marks an even-odds point for a light frost to occur later or earlier respectively. For a cautious plan, gardeners use the May 6 date, which has only a 10 % chance of a frost later, to set out tender crops, and they aim to finish harvesting tender crops by the October 4 date, which carries a 10 % chance of a frost earlier.

Hard frost at 28 °F is more damaging than a light frost at 32 °F, and the 50 % hard-frost dates are April 9 and October 27.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 6" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before October 4" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Guttenberg, IANumbered nearest stations: 1 — Lancaster, WI — 16 mi; 2 — Elkader, IA — 18 mi; 3 — Prairie Du Chien, WI — 18 mi; 4 — near Manchester, IA — 28 mi; 5 — Dubuque Lock and Dam 11, IA — 28 mi.IAWIILMN25 mi · 40 km1. Lancaster, WI — 16 mi12. Elkader, IA — 18 mi23. Prairie Du Chien, WI — 18 mi34. near Manchester, IA — 28 mi45. Dubuque Lock and Dam 11, IA — 28 mi5
  1. Lancaster, WI 16 mi (25 km)
  2. Elkader, IA 18 mi (29 km)
  3. Prairie Du Chien, WI 18 mi (30 km)
  4. near Manchester, IA 28 mi (45 km)
  5. Dubuque Lock and Dam 11, IA 28 mi (46 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.7858, -91.0958.