U.S. Frost Dates by Weather Station

NOAA station USC00473405 · Wisconsin

Frost Dates for Hancock Experiment Farm, WI

NOAA weather station Hancock Experiment Farm (USC00473405), Wisconsin · elevation 1092 ft (333 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 24only 1 spring in 10 still has a frost later
  • Typical last frostMay 1050% chance of a frost after it
  • Typical first fall frostOctober 350% chance of a frost before it
  • Frost-free season146 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Hancock Experiment Farm, WISpring: a frost after April 25 in 9 years out of 10, after May 10 in half of the years, after May 24 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 10First frost ~Oct 3Frost season at Hancock Experiment Farm, WISpring: a frost after April 25 in 9 years out of 10, after May 10 in half of the years, after May 24 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 146 days.JFMAMJJASONDLast frost ~May 10First frost ~Oct 3
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 24September 20
50% (typical)May 10October 3
90% (likely)April 25October 16
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 14

The last 15 years (2006–2020 normals)

Typical last frost May 9 (1 day earlier than the 30-year normal), typical first fall frost October 7 (4 days later). Frost-free season 148 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 Hancock Experiment Farm: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 24, 20% May 20, 30% May 16, 40% May 13, 50% May 10, 60% May 7, 70% May 3, 80% April 30, 90% April 25. Observed last spring frost in recent years: 2021 May 29, 2022 May 23, 2023 May 15, 2024 April 25.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 24May 10Apr 252021: May 292022: May 232023: May 152024: April 25Fall at Hancock Experiment Farm: chance of a frost before this dateFall, chance of a frost before the date: 10% September 20, 20% September 24, 30% September 27, 40% October 1, 50% October 3, 60% October 6, 70% October 8, 80% October 12, 90% October 16. Observed first fall frost in recent years: 2021 October 17, 2022 September 28, 2023 October 10, 2024 October 16.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 20Oct 3Oct 162021: October 172022: September 282023: October 102024: October 16
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 17
2022May 23September 28
2023May 15October 10
2024April 25October 16
2025no datano data
2026no dataseason not over yet

What these dates mean

May 24 is the cautious spring light-frost date, with only a 10% chance of a frost later than that date, and it lets a gardener plan to set out tender crops for growers.

The 50% light-frost dates are May 10 in spring and October 3 in fall; each marks an even chance of a frost occurring.

For a cautious fall plan, September 20 carries a 10% chance of a frost earlier than that date, giving a reliable window to finish harvesting tender crops. The median hard-frost dates are April 30 in spring and October 14 in fall, and a hard frost at 28 °F can damage plants that survive a light frost at 32 °F. The record spans 26 years of observations.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 24" 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 20" 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 Hancock Experiment Farm, WINumbered nearest stations: 1 — Montello, WI — 26 mi; 2 — Stevens Point, WI — 27 mi; 3 — Waupaca, WI — 29 mi; 4 — Mauston, WI — 35 mi; 5 — Wisconsin Dells, WI — 37 mi.25 mi · 40 km1. Montello, WI — 26 mi12. Stevens Point, WI — 27 mi23. Waupaca, WI — 29 mi34. Mauston, WI — 35 mi45. Wisconsin Dells, WI — 37 mi5
  1. Montello, WI 26 mi (41 km)
  2. Stevens Point, WI 27 mi (44 km)
  3. Waupaca, WI 29 mi (46 km)
  4. Mauston, WI 35 mi (56 km)
  5. Wisconsin Dells, WI 37 mi (60 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: 44.1186, -89.5358.