U.S. Frost Dates by Weather Station

NOAA station USC00134894 · Iowa

Frost Dates for Logan, IA

NOAA weather station Logan (USC00134894), Iowa · elevation 990 ft (302 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 13only 1 spring in 10 still has a frost later
  • Typical last frostApril 2950% chance of a frost after it
  • Typical first fall frostOctober 850% chance of a frost before it
  • Frost-free season162 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Logan, IASpring: a frost after April 15 in 9 years out of 10, after April 29 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 8 in half of the years, before October 22 in 9 years out of 10. Typical frost-free season: 162 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 29First frost ~Oct 8Frost season at Logan, IASpring: a frost after April 15 in 9 years out of 10, after April 29 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 8 in half of the years, before October 22 in 9 years out of 10. Typical frost-free season: 162 days.JFMAMJJASONDLast frost ~Apr 29First frost ~Oct 8
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 13September 23
50% (typical)April 29October 8
90% (likely)April 15October 22
Frost-free season (32°F, 50% chance)
162 days
Hard frost (28°F), last in spring, 50% chance after
April 19
Hard frost (28°F), first in fall, 50% chance before
October 19

The last 15 years (2006–2020 normals)

Typical last frost April 29 (same as the 30-year normal), typical first fall frost October 13 (5 days later). Frost-free season 166 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 Logan: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 13, 20% May 7, 30% May 4, 40% May 1, 50% April 29, 60% April 26, 70% April 24, 80% April 20, 90% April 15. Observed last spring frost in recent years: 2023 May 3, 2024 April 22, 2025 April 15, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 13Apr 29Apr 152023: May 32024: April 222025: April 152026: May 7Fall at Logan: chance of a frost before this dateFall, chance of a frost before the date: 10% September 23, 20% September 29, 30% October 2, 40% October 5, 50% October 8, 60% October 12, 70% October 15, 80% October 18, 90% October 22. Observed first fall frost in recent years: 2022 October 8, 2023 October 28, 2024 October 14, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 23Oct 8Oct 222022: October 82023: October 282024: October 142025: 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
2021no dataincomplete record
2022incomplete recordOctober 8
2023May 3October 28
2024April 22October 14
2025April 15October 23
2026May 7season not over yet

What these dates mean

September 23 is the cautious fall date in Logan for finishing the harvest, marking the point when there is only a 10 % chance that a light frost has arrived earlier.

The 50% light-frost date in spring is April 29; there is a 50 % chance of a frost later than this date. The 50% light-frost date in fall is October 8; there is a 50 % chance of a frost earlier than this date. The median hard-frost dates are April 19 and October 19, and hard frosts at 28 °F can damage plants more severely than light frosts at 32 °F.

For a cautious spring plan, May 13 is used as the light-frost date with only a 10 % chance of frost later, while planting on April 15 would be a gamble with a 90 % chance of frost later. In the fall, the cautious date to complete tender crops is September 23, whereas extending to October 22 would be a gamble with a 90 % chance of an earlier 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 13" 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 23" 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 Logan, IANumbered nearest stations: 1 — near Omaha, NE — 23 mi; 2 — Castana Experiment Farm, IA — 29 mi; 3 — Oakland, IA — 31 mi; 4 — near Mapleton, IA — 36 mi; 5 — Denison, IA — 36 mi.IANE25 mi · 40 km1. near Omaha, NE — 23 mi12. Castana Experiment Farm, IA — 29 mi23. Oakland, IA — 31 mi34. near Mapleton, IA — 36 mi45. Denison, IA — 36 mi5
  1. near Omaha, NE 23 mi (38 km)
  2. Castana Experiment Farm, IA 29 mi (47 km)
  3. Oakland, IA 31 mi (50 km)
  4. near Mapleton, IA 36 mi (58 km)
  5. Denison, IA 36 mi (58 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: 41.6381, -95.7883.