U.S. Frost Dates by Weather Station

NOAA station USC00132864 · Iowa

Frost Dates for Fayette, IA

NOAA weather station Fayette (USC00132864), Iowa · elevation 1145 ft (349 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 17only 1 spring in 10 still has a frost later
  • Typical last frostMay 450% chance of a frost after it
  • Typical first fall frostOctober 450% chance of a frost before it
  • Frost-free season151 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Fayette, IASpring: a frost after April 20 in 9 years out of 10, after May 4 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 4 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 151 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 4First frost ~Oct 4Frost season at Fayette, IASpring: a frost after April 20 in 9 years out of 10, after May 4 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 4 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 151 days.JFMAMJJASONDLast frost ~May 4First frost ~Oct 4
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 17September 20
50% (typical)May 4October 4
90% (likely)April 20October 18
Frost-free season (32°F, 50% chance)
151 days
Hard frost (28°F), last in spring, 50% chance after
April 25
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 3 (1 day earlier than the 30-year normal), typical first fall frost October 10 (6 days later). Frost-free season 157 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 at Fayette: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 17, 20% May 12, 30% May 9, 40% May 7, 50% May 4, 60% May 2, 70% April 29, 80% April 25, 90% April 20. Observed last spring frost in recent years: 2021 May 11, 2022 May 4, 2023 April 27, 2024 April 24, 2025 April 17, 2026 April 21.Spring: last frostChance of a frost after this date10%50%90%May 1May 17May 4Apr 202021: May 112022: May 42023: April 272024: April 242025: April 172026: April 21Fall at Fayette: chance of a frost before this dateFall, chance of a frost before the date: 10% September 20, 20% September 25, 30% September 29, 40% October 1, 50% October 4, 60% October 6, 70% October 9, 80% October 13, 90% October 18. Observed first fall frost in recent years: 2021 October 17, 2022 September 28, 2023 October 10, 2024 October 7, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 20Oct 4Oct 182021: October 172022: September 282023: October 102024: October 72025: October 23
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
2021May 11October 17
2022May 4September 28
2023April 27October 10
2024April 24October 7
2025April 17October 23
2026April 21season not over yet

What these dates mean

September 20 is the cautious fall date for finishing the harvest in Fayette, because there is only a 10 % chance that a light frost has already arrived by then. In spring the cautious date for setting out tender crops is May 17, when a light frost later than that date occurs with just a 10 % probability. Planting before April 20 carries a 90 % chance of a light frost, while waiting until after September 20 raises the risk of a frost hitting crops before they are harvested.

May 4 and October 4 are the 50 % light-frost dates; at each of these points a gardener faces an even chance of a frost having happened earlier or later. The 50 % hard-frost dates are April 25 in spring and October 15 in fall, marking the median moment a 28 °F frost is as likely as not. A hard frost matters more than a light frost because the lower temperature can damage plant tissue that survives a light frost.

How to read the probabilities

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

  • Spring: "10% after May 17" 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 September 20" 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 Fayette, IANumbered nearest stations: 1 — Elkader, IA — 20 mi; 2 — Tripoli, IA — 22 mi; 3 — New Hampton, IA — 27 mi; 4 — Decorah, IA — 29 mi; 5 — near Manchester, IA — 34 mi.WIMNIL25 mi · 40 km1. Elkader, IA — 20 mi12. Tripoli, IA — 22 mi23. New Hampton, IA — 27 mi34. Decorah, IA — 29 mi45. near Manchester, IA — 34 mi5
  1. Elkader, IA 20 mi (33 km)
  2. Tripoli, IA 22 mi (36 km)
  3. New Hampton, IA 27 mi (43 km)
  4. Decorah, IA 29 mi (47 km)
  5. near Manchester, IA 34 mi (55 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: 42.8825, -91.8303.