U.S. Frost Dates by Weather Station

NOAA station USC00135086 · Iowa

Frost Dates near Manchester, IA

NOAA weather station Manchester #2 (USC00135086), Iowa · elevation 990 ft (302 m) · hardiness zone 5a*

Manchester is the nearest town to the station (0.7 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 16only 1 spring in 10 still has a frost later
  • Typical last frostMay 350% chance of a frost after it
  • Typical first fall frostOctober 450% chance of a frost before it
  • Frost-free season154 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season near Manchester, IASpring: a frost after April 18 in 9 years out of 10, after May 3 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 4 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 154 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 3First frost ~Oct 4Frost season near Manchester, IASpring: a frost after April 18 in 9 years out of 10, after May 3 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 4 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 154 days.JFMAMJJASONDLast frost ~May 3First frost ~Oct 4
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 16September 22
50% (typical)May 3October 4
90% (likely)April 18October 17
Frost-free season (32°F, 50% chance)
154 days
Hard frost (28°F), last in spring, 50% chance after
April 23
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 2 (1 day earlier than the 30-year normal), typical first fall frost October 9 (5 days later). Frost-free season 159 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 Manchester: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 16, 20% May 12, 30% May 9, 40% May 6, 50% May 3, 60% April 30, 70% April 28, 80% April 24, 90% April 18. Observed last spring frost in recent years: 2021 May 29, 2022 May 4, 2023 April 27, 2024 April 23, 2025 April 17, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 16May 3Apr 182021: May 292022: May 42023: April 272024: April 232025: April 172026: May 7Fall near Manchester: chance of a frost before this dateFall, chance of a frost before the date: 10% September 22, 20% September 26, 30% September 30, 40% October 2, 50% October 4, 60% October 7, 70% October 10, 80% October 12, 90% October 17. Observed first fall frost in recent years: 2021 October 22, 2022 September 28, 2023 October 10, 2024 October 16, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 22Oct 4Oct 172021: October 222022: September 282023: October 102024: 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
2021May 29October 22
2022May 4September 28
2023April 27October 10
2024April 23October 16
2025April 17October 23
2026May 7season not over yet

What these dates mean

May 16 is the cautious spring date for the Manchester area; with only a 10 % chance of a light frost later, a gardener can plan to set out tender crops on that day. The 50 % date of May 3 represents the point at which the chance of a frost later is even, while the hard-frost 50 % date of April 23 marks the median time a 28 °F frost could occur; a hard frost at 28 °F can damage or kill plants that survive a light frost at 32 °F.

In the fall, September 22 serves as the cautious date, offering just a 10 % chance that a light frost has arrived earlier, so it is a good deadline to finish harvesting tender crops. The 50 % date of October 4 gives an even chance of a frost occurring earlier, and the hard-frost 50 % date of October 15 indicates the median timing of a 28 °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 16" 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 22" 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 Manchester, IANumbered nearest stations: 1 — Elkader, IA — 21 mi; 2 — Cascade, IA — 26 mi; 3 — near Guttenberg, IA — 28 mi; 4 — near Marion, IA — 30 mi; 5 — Fayette, IA — 34 mi.IAWIIL25 mi · 40 km1. Elkader, IA — 21 mi12. Cascade, IA — 26 mi23. near Guttenberg, IA — 28 mi34. near Marion, IA — 30 mi45. Fayette, IA — 34 mi5
  1. Elkader, IA 21 mi (34 km)
  2. Cascade, IA 26 mi (41 km)
  3. near Guttenberg, IA 28 mi (45 km)
  4. near Marion, IA 30 mi (48 km)
  5. Fayette, IA 34 mi (55 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: 42.4733, -91.4517.