U.S. Frost Dates by Weather Station

NOAA station USC00135837 · Iowa

Frost Dates for Muscatine, IA

NOAA weather station Muscatine (USC00135837), Iowa · elevation 549 ft (167 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 9only 1 spring in 10 still has a frost later
  • Typical last frostApril 2450% chance of a frost after it
  • Typical first fall frostOctober 1450% chance of a frost before it
  • Frost-free season172 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Muscatine, IASpring: a frost after April 9 in 9 years out of 10, after April 24 in half of the years, after May 9 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 14 in half of the years, before October 25 in 9 years out of 10. Typical frost-free season: 172 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 24First frost ~Oct 14Frost season at Muscatine, IASpring: a frost after April 9 in 9 years out of 10, after April 24 in half of the years, after May 9 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 14 in half of the years, before October 25 in 9 years out of 10. Typical frost-free season: 172 days.JFMAMJJASONDLast frost ~Apr 24First frost ~Oct 14
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 9October 1
50% (typical)April 24October 14
90% (likely)April 9October 25
Frost-free season (32°F, 50% chance)
172 days
Hard frost (28°F), last in spring, 50% chance after
April 13
Hard frost (28°F), first in fall, 50% chance before
October 23

The last 15 years (2006–2020 normals)

Typical last frost April 24 (same as the 30-year normal), typical first fall frost October 17 (3 days later). Frost-free season 175 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 Muscatine: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 9, 20% May 4, 30% April 30, 40% April 27, 50% April 24, 60% April 21, 70% April 17, 80% April 14, 90% April 9. Observed last spring frost in recent years: 2023 April 27, 2024 April 22, 2025 April 17, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 9Apr 24Apr 92023: April 272024: April 222025: April 172026: May 7Fall at Muscatine: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 5, 30% October 8, 40% October 11, 50% October 14, 60% October 16, 70% October 19, 80% October 21, 90% October 25. Observed first fall frost in recent years: 2021 November 1, 2022 October 8, 2023 October 30, 2024 October 16, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 14Oct 252021: November 12022: October 82023: October 302024: October 162025: 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
2021incomplete recordNovember 1
2022incomplete recordOctober 8
2023April 27October 30
2024April 22October 16
2025April 17October 23
2026May 7season not over yet

What these dates mean

May 9 is the cautious spring date for Muscatine; with only a 10% chance of a light frost later, it gives a gardener a reliable point to set out tender crops.

April 24 marks the 50% light-frost date in spring, meaning a gardener has a 50% chance of a light frost later in the season. In the autumn, October 1 is the cautious date for finishing tender crops, as there is only a 10% chance that a light frost has already arrived. The median autumn light-frost date is October 14, when the chance of a light frost having arrived is 50%. These probabilities are based on a 30-year record of observations.

The hard-frost median dates are April 13 and October 23, and a hard frost can damage plant tissue more severely than 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 9" 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 1" 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 Muscatine, IANumbered nearest stations: 1 — Aledo, IL — 22 mi; 2 — Iowa City, IA — 26 mi; 3 — near Rock Island, IL — 27 mi; 4 — near Moline, IL — 29 mi; 5 — Washington, IA — 34 mi.IAIL25 mi · 40 km1. Aledo, IL — 22 mi12. Iowa City, IA — 26 mi23. near Rock Island, IL — 27 mi34. near Moline, IL — 29 mi45. Washington, IA — 34 mi5
  1. Aledo, IL 22 mi (36 km)
  2. Iowa City, IA 26 mi (42 km)
  3. near Rock Island, IL 27 mi (44 km)
  4. near Moline, IL 29 mi (46 km)
  5. Washington, 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: 41.4075, -91.0728.