U.S. Frost Dates by Weather Station

NOAA station USC00474937 · Wisconsin

Frost Dates for Lynxville Dam 9, WI

NOAA weather station Lynxville Dam 9 (USC00474937), Wisconsin · elevation 633 ft (193 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 8only 1 spring in 10 still has a frost later
  • Typical last frostApril 2450% chance of a frost after it
  • Typical first fall frostOctober 1750% chance of a frost before it
  • Frost-free season175 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Lynxville Dam 9, WISpring: a frost after April 9 in 9 years out of 10, after April 24 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 17 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 175 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 24First frost ~Oct 17Frost season at Lynxville Dam 9, WISpring: a frost after April 9 in 9 years out of 10, after April 24 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 17 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 175 days.JFMAMJJASONDLast frost ~Apr 24First frost ~Oct 17
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 8October 4
50% (typical)April 24October 17
90% (likely)April 9October 28
Frost-free season (32°F, 50% chance)
175 days
Hard frost (28°F), last in spring, 50% chance after
April 11
Hard frost (28°F), first in fall, 50% chance before
October 27

The last 15 years (2006–2020 normals)

Typical last frost April 23 (1 day earlier than the 30-year normal), typical first fall frost October 20 (3 days later). Frost-free season 179 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 Lynxville Dam 9: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 8, 20% May 3, 30% May 1, 40% April 28, 50% April 24, 60% April 21, 70% April 17, 80% April 14, 90% April 9. Observed last spring frost in recent years: 2021 April 22, 2022 April 27, 2023 April 27, 2024 April 22, 2025 April 17, 2026 April 8.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 8Apr 24Apr 92021: April 222022: April 272023: April 272024: April 222025: April 172026: April 8Fall at Lynxville Dam 9: chance of a frost before this dateFall, chance of a frost before the date: 10% October 4, 20% October 8, 30% October 11, 40% October 14, 50% October 17, 60% October 19, 70% October 21, 80% October 24, 90% October 28. Observed first fall frost in recent years: 2021 November 2, 2022 October 14, 2023 October 30, 2024 October 16, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 4Oct 17Oct 282021: November 22022: October 142023: October 302024: October 162025: October 24
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 22November 2
2022April 27October 14
2023April 27October 30
2024April 22October 16
2025April 17October 24
2026April 8season not over yet

What these dates mean

May 8 is the cautious spring light-frost date at Lynxville Dam 9, with only a 10 % chance that a frost will occur later; this gives a gardener enough confidence to set out tender crops reliably.

The 50 % light-frost dates are April 24 in spring and October 17 in fall; each marks the point where the odds of a frost are even. October 4 is the cautious fall light-frost date, carrying a 10 % chance that a frost has arrived earlier, and it signals when tender crops should be finished harvesting.

Hard-frost dates, when temperatures reach 28 °F, are April 11 in spring and October 27 in fall, and a hard frost can damage plants more severely than a light frost because the colder temperature can kill tissue that survives 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 8" 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 4" 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 Lynxville Dam 9, WINumbered nearest stations: 1 — Prairie Du Chien, WI — 11 mi; 2 — Gays Mills, WI — 14 mi; 3 — Genoa Dam 8, WI — 26 mi; 4 — Viroqua, WI — 26 mi; 5 — near Guttenberg, IA — 29 mi.WIIAMNIL25 mi · 40 km1. Prairie Du Chien, WI — 11 mi12. Gays Mills, WI — 14 mi23. Genoa Dam 8, WI — 26 mi34. Viroqua, WI — 26 mi45. near Guttenberg, IA — 29 mi5
  1. Prairie Du Chien, WI 11 mi (18 km)
  2. Gays Mills, WI 14 mi (23 km)
  3. Genoa Dam 8, WI 26 mi (41 km)
  4. Viroqua, WI 26 mi (43 km)
  5. near Guttenberg, IA 29 mi (47 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: 43.2117, -91.0986.