U.S. Frost Dates by Weather Station

NOAA station USC00132603 · Iowa

Frost Dates for Elkader, IA

NOAA weather station Elkader 6 SSW (USC00132603), Iowa · elevation 788 ft (240 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 850% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season146 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Elkader, IASpring: a frost after April 24 in 9 years out of 10, after May 8 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 18 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 1Frost season at Elkader, IASpring: a frost after April 24 in 9 years out of 10, after May 8 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 18 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 146 days.JFMAMJJASONDLast frost ~May 8First frost ~Oct 1
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 22September 18
50% (typical)May 8October 1
90% (likely)April 24October 14
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 11

The last 15 years (2006–2020 normals)

Typical last frost May 5 (3 days earlier than the 30-year normal), typical first fall frost October 6 (5 days later). Frost-free season 153 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 Elkader: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 17, 30% May 14, 40% May 11, 50% May 8, 60% May 5, 70% May 2, 80% April 29, 90% April 24. Observed last spring frost in recent years: 2021 May 29, 2022 May 23, 2023 May 26, 2024 April 25, 2025 April 20, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 8Apr 242021: May 292022: May 232023: May 262024: April 252025: April 202026: May 11Fall at Elkader: chance of a frost before this dateFall, chance of a frost before the date: 10% September 18, 20% September 22, 30% September 26, 40% September 29, 50% October 1, 60% October 4, 70% October 6, 80% October 10, 90% October 14. Observed first fall frost in recent years: 2021 October 17, 2022 September 28, 2023 October 9, 2024 October 7, 2025 October 9.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 18Oct 1Oct 142021: October 172022: September 282023: October 92024: October 72025: October 9
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 29October 17
2022May 23September 28
2023May 26October 9
2024April 25October 7
2025April 20October 9
2026May 11season not over yet

What these dates mean

May 22 is the cautious spring date for light frost in Elkader; with only a 10 % chance of frost later, it lets a gardener set out tender crops with confidence after the risk has largely passed.

The 50 % dates are the points at which frost is equally likely to have occurred or not. In spring the median light-frost date is May 8, and the median hard-frost (28 °F) date is April 27. In fall the median light-frost date is October 1, and the median hard-frost date is October 11. For a careful fall schedule the September 18 date carries a 10 % chance of frost earlier, so it marks the cautious deadline to finish harvesting tender crops, while October 14 would be a gamble.

A hard frost matters more than a light frost because the lower temperature of 28 °F can damage plant tissue that survives the milder 32 °F exposure.

How to read the probabilities

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

  • Spring: "10% after May 22" 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 18" 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 Elkader, IANumbered nearest stations: 1 — near Guttenberg, IA — 18 mi; 2 — Fayette, IA — 20 mi; 3 — near Manchester, IA — 21 mi; 4 — Prairie Du Chien, WI — 25 mi; 5 — Lancaster, WI — 34 mi.IAWIIL25 mi · 40 km1. near Guttenberg, IA — 18 mi12. Fayette, IA — 20 mi23. near Manchester, IA — 21 mi34. Prairie Du Chien, WI — 25 mi45. Lancaster, WI — 34 mi5
  1. near Guttenberg, IA 18 mi (29 km)
  2. Fayette, IA 20 mi (33 km)
  3. near Manchester, IA 21 mi (34 km)
  4. Prairie Du Chien, WI 25 mi (40 km)
  5. Lancaster, WI 34 mi (55 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.7753, -91.4536.