U.S. Frost Dates by Weather Station

NOAA station USC00131442 · Iowa

Frost Dates for Cherokee, IA

NOAA weather station Cherokee (USC00131442), Iowa · elevation 1210 ft (369 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 season152 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Cherokee, 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: 152 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 4First frost ~Oct 4Frost season at Cherokee, 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: 152 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)
152 days
Hard frost (28°F), last in spring, 50% chance after
April 24
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 4 (same as the 30-year normal), typical first fall frost October 6 (2 days later). Frost-free season 156 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 Cherokee: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 17, 20% May 13, 30% May 9, 40% May 6, 50% May 4, 60% May 1, 70% April 29, 80% April 25, 90% April 20. Observed last spring frost in recent years: 2021 May 12, 2022 May 22, 2023 May 4, 2024 April 24, 2025 May 4, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1May 17May 4Apr 202021: May 122022: May 222023: May 42024: April 242025: May 42026: May 11Fall at Cherokee: 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 16, 2022 September 28, 2023 October 7, 2024 October 7, 2025 October 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 20Oct 4Oct 182021: October 162022: September 282023: October 72024: October 72025: October 22
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 12October 16
2022May 22September 28
2023May 4October 7
2024April 24October 7
2025May 4October 22
2026May 11season not over yet

What these dates mean

May 17 is the cautious spring date, giving a gardener enough confidence to set out tender crops. It marks a point when the chance of a later frost drops to 10%.

The 50% date in spring is May 4, meaning there is an even chance of a frost occurring. The 50% date in fall is October 4, meaning there is an even chance of a frost occurring. September 20 is the cautious fall date, showing a low 10% chance of an earlier frost and allowing a gardener to finish harvesting tender crops. The hard-frost 50% dates are April 24 in spring and October 15 in fall; a hard frost at 28°F can damage plants more severely than a light frost at 32°F.

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 Cherokee, IANumbered nearest stations: 1 — Storm Lake, IA — 19 mi; 2 — Primghar, IA — 23 mi; 3 — Sioux Rapids, IA — 26 mi; 4 — Sanborn, IA — 30 mi; 5 — Le Mars, IA — 31 mi.IASD25 mi · 40 km1. Storm Lake, IA — 19 mi12. Primghar, IA — 23 mi23. Sioux Rapids, IA — 26 mi34. Sanborn, IA — 30 mi45. Le Mars, IA — 31 mi5
  1. Storm Lake, IA 19 mi (31 km)
  2. Primghar, IA 23 mi (37 km)
  3. Sioux Rapids, IA 26 mi (41 km)
  4. Sanborn, IA 30 mi (48 km)
  5. Le Mars, IA 31 mi (50 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: 42.7572, -95.5378.