U.S. Frost Dates by Weather Station

NOAA station USW00014933 · Iowa

Frost Dates for Des Moines, IA

NOAA weather station Des Moines International Airport (USW00014933), Iowa · elevation 957 ft (292 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 2only 1 spring in 10 still has a frost later
  • Typical last frostApril 1850% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season184 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Des Moines, IASpring: a frost after April 4 in 9 years out of 10, after April 18 in half of the years, after May 2 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 20 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 184 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 18First frost ~Oct 20Frost season at Des Moines, IASpring: a frost after April 4 in 9 years out of 10, after April 18 in half of the years, after May 2 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 20 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 184 days.JFMAMJJASONDLast frost ~Apr 18First frost ~Oct 20
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 2October 4
50% (typical)April 18October 20
90% (likely)April 4November 1
Frost-free season (32°F, 50% chance)
184 days
Hard frost (28°F), last in spring, 50% chance after
April 8
Hard frost (28°F), first in fall, 50% chance before
October 30

The last 15 years (2006–2020 normals)

Typical last frost April 18 (same as the 30-year normal), typical first fall frost October 23 (3 days later). Frost-free season 186 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 Des Moines: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 2, 20% April 28, 30% April 24, 40% April 21, 50% April 18, 60% April 14, 70% April 12, 80% April 9, 90% April 4. Observed last spring frost in recent years: 2021 April 22, 2022 April 26, 2023 April 23, 2024 April 21, 2025 April 8, 2026 April 5.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 2Apr 18Apr 42021: April 222022: April 262023: April 232024: April 212025: April 82026: April 5Fall at Des Moines: chance of a frost before this dateFall, chance of a frost before the date: 10% October 4, 20% October 10, 30% October 14, 40% October 17, 50% October 20, 60% October 23, 70% October 25, 80% October 28, 90% November 1. Observed first fall frost in recent years: 2021 November 1, 2022 October 14, 2023 October 27, 2024 October 16, 2025 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 4Oct 20Nov 12021: November 12022: October 142023: October 272024: October 162025: November 2
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 26October 14
2023April 23October 27
2024April 21October 16
2025April 8November 2
2026April 5season not over yet

What these dates mean

October 4 is the cautious fall date for finishing the harvest of tender crops in Des Moines; there is only a 10% chance that a light frost has arrived before that day. Gardeners who wait until that date are minimizing the risk of frost damage, while planting after the 90% chance date of November 1 would be a gamble.

In spring, the cautious date for setting out tender crops is May 2, when the chance of a light frost later in the season is just 10%; sowing on April 4 would carry a 90% chance of a frost and is therefore risky. The 50% light-frost dates—April 18 in spring and October 20 in fall—represent the median point at which the chance of a frost is 50%. The 50% hard-frost dates, April 8 and October 30, mark when a 28 °F frost is equally likely, and hard frost matters more than a light frost because the lower temperature can cause more severe plant injury.

How to read the probabilities

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

  • Spring: "10% after May 2" 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 Des Moines, IANumbered nearest stations: 1 — Indianola, IA — 12 mi; 2 — Ankeny, IA — 14 mi; 3 — Perry, IA — 32 mi; 4 — Ames, IA — 34 mi; 5 — Newton, IA — 34 mi.25 mi · 40 km1. Indianola, IA — 12 mi12. Ankeny, IA — 14 mi23. Perry, IA — 32 mi34. Ames, IA — 34 mi45. Newton, IA — 34 mi5
  1. Indianola, IA 12 mi (19 km)
  2. Ankeny, IA 14 mi (22 km)
  3. Perry, IA 32 mi (51 km)
  4. Ames, IA 34 mi (55 km)
  5. Newton, IA 34 mi (55 km)

Sources

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

Station coordinates: 41.5339, -93.6531.