U.S. Frost Dates by Weather Station

NOAA station USC00134381 · Iowa

Frost Dates near Keokuk, IA

NOAA weather station Keokuk Lock Dam 19 (USC00134381), Iowa · elevation 527 ft (161 m) · hardiness zone 6a*

Keokuk is the nearest town to the station (0.5 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 April 26only 1 spring in 10 still has a frost later
  • Typical last frostApril 1050% chance of a frost after it
  • Typical first fall frostOctober 2750% chance of a frost before it
  • Frost-free season198 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season near Keokuk, IASpring: a frost after March 30 in 9 years out of 10, after April 10 in half of the years, after April 26 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 27 in half of the years, before November 7 in 9 years out of 10. Typical frost-free season: 198 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 10First frost ~Oct 27Frost season near Keokuk, IASpring: a frost after March 30 in 9 years out of 10, after April 10 in half of the years, after April 26 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 27 in half of the years, before November 7 in 9 years out of 10. Typical frost-free season: 198 days.JFMAMJJASONDLast frost ~Apr 10First frost ~Oct 27
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)April 26October 10
50% (typical)April 10October 27
90% (likely)March 30November 7
Frost-free season (32°F, 50% chance)
198 days
Hard frost (28°F), last in spring, 50% chance after
April 2
Hard frost (28°F), first in fall, 50% chance before
November 5

The last 15 years (2006–2020 normals)

Typical last frost April 12 (2 days later than the 30-year normal), typical first fall frost October 29 (2 days later). Frost-free season 198 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 Keokuk: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 26, 20% April 21, 30% April 17, 40% April 13, 50% April 10, 60% April 8, 70% April 5, 80% April 3, 90% March 30. Observed last spring frost in recent years: 2021 April 23, 2022 April 27, 2023 April 24, 2024 April 6, 2025 April 9, 2026 March 30.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 26Apr 10Mar 302021: April 232022: April 272023: April 242024: April 62025: April 92026: March 30Fall near Keokuk: chance of a frost before this dateFall, chance of a frost before the date: 10% October 10, 20% October 16, 30% October 21, 40% October 24, 50% October 27, 60% October 29, 70% November 1, 80% November 3, 90% November 7. Observed first fall frost in recent years: 2021 November 2, 2022 October 18, 2023 October 30, 2024 November 26, 2025 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 10Oct 27Nov 72021: November 22022: October 182023: October 302024: November 262025: 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 23November 2
2022April 27October 18
2023April 24October 30
2024April 6November 26
2025April 9November 2
2026March 30season not over yet

What these dates mean

April 26, the cautious spring date for the Keokuk area, lets a gardener plan to set out tender crops with only a 10 % chance that a light frost will occur later. By contrast, planting on March 30 carries a 90 % chance of a later frost and is therefore a gamble.

The 50 % spring date is April 10, meaning there is an even chance of a light frost occurring on either side of that day, while the 50 % fall date is October 27 with an equal chance of a frost occurring earlier or later. For a cautious fall schedule, October 10 provides a 10 % chance that a light frost has arrived earlier, whereas November 7 would be a gamble. The 50 % hard-frost dates are April 2 and November 5, and hard frost at 28 °F matters more than light frost at 32 °F 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 April 26" 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 10" 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 Keokuk, IANumbered nearest stations: 1 — Bentley, IL — 14 mi; 2 — Fort Madison, IA — 16 mi; 3 — near Canton, MO — 19 mi; 4 — near Burlington, IA — 29 mi; 5 — Burlington (Airport), IA — 30 mi.ILMOIA25 mi · 40 km1. Bentley, IL — 14 mi12. Fort Madison, IA — 16 mi23. near Canton, MO — 19 mi34. near Burlington, IA — 29 mi45. Burlington (Airport), IA — 30 mi5
  1. Bentley, IL 14 mi (23 km)
  2. Fort Madison, IA 16 mi (25 km)
  3. near Canton, MO 19 mi (31 km)
  4. near Burlington, IA 29 mi (47 km)
  5. Burlington (Airport), IA 30 mi (48 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.3967, -91.375.