U.S. Frost Dates by Weather Station

NOAA station USC00131533 · Iowa

Frost Dates for Clarinda, IA

NOAA weather station Clarinda (USC00131533), Iowa · elevation 980 ft (299 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 7only 1 spring in 10 still has a frost later
  • Typical last frostApril 2550% chance of a frost after it
  • Typical first fall frostOctober 1150% chance of a frost before it
  • Frost-free season168 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Clarinda, IASpring: a frost after April 11 in 9 years out of 10, after April 25 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 11 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 168 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 25First frost ~Oct 11Frost season at Clarinda, IASpring: a frost after April 11 in 9 years out of 10, after April 25 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 11 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 168 days.JFMAMJJASONDLast frost ~Apr 25First frost ~Oct 11
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.Today

Frost dates (32°F)

Probability of frost, based on 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 7September 26
50% (typical)April 25October 11
90% (likely)April 11October 24
Frost-free season (32°F, 50% chance)
168 days
Hard frost (28°F), last in spring, 50% chance after
April 14
Hard frost (28°F), first in fall, 50% chance before
October 21

The last 15 years (2006–2020 normals)

Typical last frost April 26 (1 day later than the 30-year normal), typical first fall frost October 13 (2 days later). Frost-free season 170 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 Clarinda: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 7, 20% May 3, 30% April 30, 40% April 27, 50% April 25, 60% April 22, 70% April 18, 80% April 15, 90% April 11. Observed last spring frost in recent years: 2021 May 5, 2022 April 27, 2023 May 4, 2024 April 21, 2025 April 17, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 7Apr 25Apr 112021: May 52022: April 272023: May 42024: April 212025: April 172026: May 2Fall at Clarinda: chance of a frost before this dateFall, chance of a frost before the date: 10% September 26, 20% October 1, 30% October 4, 40% October 8, 50% October 11, 60% October 14, 70% October 17, 80% October 20, 90% October 24. Observed first fall frost in recent years: 2021 October 17, 2022 October 8, 2023 October 11, 2024 October 15, 2025 October 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 26Oct 11Oct 242021: October 172022: October 82023: October 112024: October 152025: 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 5October 17
2022April 27October 8
2023May 4October 11
2024April 21October 15
2025April 17October 22
2026May 2season not over yet

What these dates mean

In Clarinda there are 168 days between the 50% dates of April 25 and October 11, defining the span in which a light frost is as likely to have occurred as not. These 50% dates are reference points only; they are not themselves frost dates but show when the odds of a 32 °F frost are even.

For a cautious planting plan, gardeners should wait until the May 7 spring light-frost date, which carries only a 10 % chance of a frost later, and should aim to finish tender crops by the September 26 fall light-frost date, which carries only a 10 % chance of a frost earlier. The early-spring gamble of April 11 holds a 90 % chance of later frost, while the late-fall gamble of October 24 holds a 90 % chance of earlier frost. The hard-frost 50% dates are April 14 in spring and October 21 in fall; a hard frost at 28 °F can damage plants that would survive 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 7" 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 26" 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 Clarinda, IANumbered nearest stations: 1 — Bedford, IA — 16 mi; 2 — Shenandoah, IA — 18 mi; 3 — Red Oak, IA — 23 mi; 4 — Maryville, MO — 28 mi; 5 — Sidney, IA — 33 mi.IANEMO25 mi · 40 km1. Bedford, IA — 16 mi12. Shenandoah, IA — 18 mi23. Red Oak, IA — 23 mi34. Maryville, MO — 28 mi45. Sidney, IA — 33 mi5
  1. Bedford, IA 16 mi (25 km)
  2. Shenandoah, IA 18 mi (29 km)
  3. Red Oak, IA 23 mi (36 km)
  4. Maryville, MO 28 mi (45 km)
  5. Sidney, IA 33 mi (53 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: 40.7244, -95.0192.