U.S. Frost Dates by Weather Station

NOAA station USC00134561 · Iowa

Frost Dates for Lake Park, IA

NOAA weather station Lake Park (USC00134561), Iowa · elevation 1465 ft (447 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 1050% chance of a frost before it
  • Frost-free season164 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Lake Park, IASpring: a frost after April 12 in 9 years out of 10, after April 30 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 10 in half of the years, before October 22 in 9 years out of 10. Typical frost-free season: 164 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 10Frost season at Lake Park, IASpring: a frost after April 12 in 9 years out of 10, after April 30 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 10 in half of the years, before October 22 in 9 years out of 10. Typical frost-free season: 164 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 10
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 11September 26
50% (typical)April 30October 10
90% (likely)April 12October 22
Frost-free season (32°F, 50% chance)
164 days
Hard frost (28°F), last in spring, 50% chance after
April 18
Hard frost (28°F), first in fall, 50% chance before
October 20

The last 15 years (2006–2020 normals)

Typical last frost May 1 (1 day later than the 30-year normal), typical first fall frost October 12 (2 days later). Frost-free season 165 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 Lake Park: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 7, 30% May 4, 40% May 2, 50% April 30, 60% April 26, 70% April 23, 80% April 19, 90% April 12. Observed last spring frost in recent years: 2021 May 11, 2022 April 27, 2023 May 3, 2024 April 25, 2025 April 27, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 30Apr 122021: May 112022: April 272023: May 32024: April 252025: April 272026: May 11Fall at Lake Park: chance of a frost before this dateFall, chance of a frost before the date: 10% September 26, 20% October 1, 30% October 4, 40% October 6, 50% October 10, 60% October 13, 70% October 17, 80% October 19, 90% October 22. Observed first fall frost in recent years: 2021 October 30, 2022 October 8, 2023 October 7, 2024 October 7, 2025 October 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 26Oct 10Oct 222021: October 302022: October 82023: October 72024: October 72025: October 22
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 11October 30
2022April 27October 8
2023May 3October 7
2024April 25October 7
2025April 27October 22
2026May 11season not over yet

What these dates mean

The 164 days between the 50% dates in Lake Park mark the interval from the median light-frost date of April 30 to the median light-frost date of October 10. For a gardener this period represents the span when a light frost (32 °F) is equally likely to have occurred or not, and it defines the central window for planning planting and harvest activities. The corresponding 50% hard-frost dates are April 18 in spring and October 20 in fall; these are the moments when a hard frost (28 °F) has an even chance of having happened.

In spring the cautious date for setting out tender crops is the late light-frost date of May 11, which carries only a 10 % chance of a later frost. In fall the cautious date to finish harvesting tender crops is the early light-frost date of September 26, also with a 10 % chance of an earlier frost. A hard frost at 28 °F can damage plants that would otherwise survive a light frost at 32 °F.

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 September 26" 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 Lake Park, IANumbered nearest stations: 1 — Milford, IA — 8 mi; 2 — Worthington, MN — 19 mi; 3 — Sibley, IA — 21 mi; 4 — Spencer, IA — 22 mi; 5 — Sanborn, IA — 25 mi.MNSD25 mi · 40 km1. Milford, IA — 8 mi12. Worthington, MN — 19 mi23. Sibley, IA — 21 mi34. Spencer, IA — 22 mi45. Sanborn, IA — 25 mi5
  1. Milford, IA 8 mi (13 km)
  2. Worthington, MN 19 mi (30 km)
  3. Sibley, IA 21 mi (35 km)
  4. Spencer, IA 22 mi (35 km)
  5. Sanborn, IA 25 mi (40 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: 43.4483, -95.3247.