U.S. Frost Dates by Weather Station

NOAA station USC00476827 · Wisconsin

Frost Dates for Prairie Du Chien, WI

NOAA weather station Prairie Du Chien (USC00476827), Wisconsin · elevation 658 ft (201 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2850% chance of a frost after it
  • Typical first fall frostOctober 1250% chance of a frost before it
  • Frost-free season166 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Prairie Du Chien, WISpring: a frost after April 14 in 9 years out of 10, after April 28 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 12 in half of the years, before October 25 in 9 years out of 10. Typical frost-free season: 166 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 28First frost ~Oct 12Frost season at Prairie Du Chien, WISpring: a frost after April 14 in 9 years out of 10, after April 28 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 12 in half of the years, before October 25 in 9 years out of 10. Typical frost-free season: 166 days.JFMAMJJASONDLast frost ~Apr 28First frost ~Oct 12
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 27
50% (typical)April 28October 12
90% (likely)April 14October 25
Frost-free season (32°F, 50% chance)
166 days
Hard frost (28°F), last in spring, 50% chance after
April 16
Hard frost (28°F), first in fall, 50% chance before
October 22

The last 15 years (2006–2020 normals)

Typical last frost April 27 (1 day earlier than the 30-year normal), typical first fall frost October 16 (4 days later). Frost-free season 171 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 Prairie Du Chien: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 6, 30% May 3, 40% April 30, 50% April 28, 60% April 25, 70% April 22, 80% April 18, 90% April 14. Observed last spring frost in recent years: 2021 April 25, 2022 April 20, 2023 April 27, 2024 April 23, 2025 April 17, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 28Apr 142021: April 252022: April 202023: April 272024: April 232025: April 172026: May 7Fall at Prairie Du Chien: chance of a frost before this dateFall, chance of a frost before the date: 10% September 27, 20% October 2, 30% October 6, 40% October 9, 50% October 12, 60% October 14, 70% October 17, 80% October 20, 90% October 25. Observed first fall frost in recent years: 2021 October 23, 2022 October 8, 2023 October 11, 2024 October 7, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 27Oct 12Oct 252021: October 232022: October 82023: October 112024: October 72025: 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 25October 23
2022April 20October 8
2023April 27October 11
2024April 23October 7
2025April 17October 23
2026May 7season not over yet

What these dates mean

May 11, which carries a 10% chance of a light frost later, is the cautious spring date for setting out tender crops in Prairie Du Chien. The low risk marks a point of reduced frost danger for tender crops.

The 50% spring date is April 28, meaning there is a 50% chance of a light frost later than this date, while the 50% fall date is October 12, meaning there is a 50% chance of a light frost earlier than this date. The hard-frost 50% dates are April 16 and October 22; a hard frost at 28 °F can cause more severe damage than a light frost at 32 °F, making those dates especially relevant.

September 27, with a 10% chance of a light frost earlier, is the cautious fall date for finishing the harvest of tender crops.

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 27" 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 Prairie Du Chien, WINumbered nearest stations: 1 — Lynxville Dam 9, WI — 11 mi; 2 — near Guttenberg, IA — 18 mi; 3 — Gays Mills, WI — 23 mi; 4 — Lancaster, WI — 23 mi; 5 — Elkader, IA — 25 mi.IAWIMNIL25 mi · 40 km1. Lynxville Dam 9, WI — 11 mi12. near Guttenberg, IA — 18 mi23. Gays Mills, WI — 23 mi34. Lancaster, WI — 23 mi45. Elkader, IA — 25 mi5
  1. Lynxville Dam 9, WI 11 mi (18 km)
  2. near Guttenberg, IA 18 mi (30 km)
  3. Gays Mills, WI 23 mi (37 km)
  4. Lancaster, WI 23 mi (38 km)
  5. Elkader, 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: 43.0514, -91.135.