U.S. Frost Dates by Weather Station

NOAA station USC00130608 · Iowa

Frost Dates near Bellevue, IA

NOAA weather station Bellevue Lock and Dam 12 (USC00130608), Iowa · elevation 603 ft (184 m) · hardiness zone 5a*

Bellevue is the nearest town to the station (0.2 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2550% chance of a frost after it
  • Typical first fall frostOctober 1650% chance of a frost before it
  • Frost-free season172 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season near Bellevue, IASpring: a frost after April 10 in 9 years out of 10, after April 25 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 16 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 172 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 25First frost ~Oct 16Frost season near Bellevue, IASpring: a frost after April 10 in 9 years out of 10, after April 25 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 16 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 172 days.JFMAMJJASONDLast frost ~Apr 25First frost ~Oct 16
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 11October 1
50% (typical)April 25October 16
90% (likely)April 10October 29
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 27

The last 15 years (2006–2020 normals)

Typical last frost April 27 (2 days later than the 30-year normal), typical first fall frost October 19 (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 near Bellevue: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 5, 30% May 2, 40% April 29, 50% April 25, 60% April 22, 70% April 18, 80% April 15, 90% April 10. Observed last spring frost in recent years: 2021 April 22, 2022 April 20, 2023 April 27, 2024 April 23, 2025 April 17, 2026 May 9.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 25Apr 102021: April 222022: April 202023: April 272024: April 232025: April 172026: May 9Fall near Bellevue: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 7, 30% October 10, 40% October 14, 50% October 16, 60% October 19, 70% October 21, 80% October 24, 90% October 29. Observed first fall frost in recent years: 2021 October 23, 2022 October 8, 2023 October 11, 2024 October 16, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 16Oct 292021: October 232022: October 82023: October 112024: 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
2021April 22October 23
2022April 20October 8
2023April 27October 11
2024April 23October 16
2025April 17October 23
2026May 9season not over yet

What these dates mean

The 172 days between the 50% dates in the Bellevue area—April 25 and October 16—frame the span when a light frost (32 °F) is equally likely to have occurred or not, marking the middle of the seasonal risk. For a gardener, this interval shows when the probability of frost shifts from higher to lower in spring and from lower to higher in fall.

In spring, the cautious date for setting out tender crops is May 11, when there is a 10 % chance of a frost later than that day; planting on April 10 would carry a 90 % chance of a frost later and is a gamble. In fall, the cautious date to finish harvesting tender crops is October 1, when there is a 10 % chance of a frost earlier than that day; waiting until October 29 would involve a 90 % chance of a frost earlier and is a gamble.

Hard frost at 28 °F matters more than a light frost because it can damage plants that survive a 32 °F 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 11" 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 Bellevue, IANumbered nearest stations: 1 — Dubuque, IA — 17 mi; 2 — Maquoketa, IA — 18 mi; 3 — Dubuque Lock and Dam 11, IA — 22 mi; 4 — Stockton, IL — 24 mi; 5 — Cascade, IA — 30 mi.ILWI25 mi · 40 km1. Dubuque, IA — 17 mi12. Maquoketa, IA — 18 mi23. Dubuque Lock and Dam 11, IA — 22 mi34. Stockton, IL — 24 mi45. Cascade, IA — 30 mi5
  1. Dubuque, IA 17 mi (28 km)
  2. Maquoketa, IA 18 mi (29 km)
  3. Dubuque Lock and Dam 11, IA 22 mi (36 km)
  4. Stockton, IL 24 mi (39 km)
  5. Cascade, IA 30 mi (49 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: 42.2611, -90.423.