U.S. Frost Dates by Weather Station

NOAA station USC00473800 · Wisconsin

Frost Dates for Hurley, WI

NOAA weather station Hurley (USC00473800), Wisconsin · elevation 1444 ft (440 m) · hardiness zone 4b*

  • Lower-risk planting dateafter June 7only 1 spring in 10 still has a frost later
  • Typical last frostMay 2450% chance of a frost after it
  • Typical first fall frostSeptember 2850% chance of a frost before it
  • Frost-free season128 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Hurley, WISpring: a frost after May 4 in 9 years out of 10, after May 24 in half of the years, after June 7 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 28 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 128 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 24First frost ~Sep 28Frost season at Hurley, WISpring: a frost after May 4 in 9 years out of 10, after May 24 in half of the years, after June 7 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 28 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 128 days.JFMAMJJASONDLast frost ~May 24First frost ~Sep 28
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)June 7September 13
50% (typical)May 24September 28
90% (likely)May 4October 11
Frost-free season (32°F, 50% chance)
128 days
Hard frost (28°F), last in spring, 50% chance after
May 8
Hard frost (28°F), first in fall, 50% chance before
October 8

The last 15 years (2006–2020 normals)

Typical last frost May 20 (4 days earlier than the 30-year normal), typical first fall frost October 1 (3 days later). Frost-free season 133 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 Hurley: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 7, 20% June 2, 30% May 30, 40% May 27, 50% May 24, 60% May 20, 70% May 16, 80% May 11, 90% May 4. Observed last spring frost in recent years: 2021 May 30, 2022 May 23, 2023 May 3, 2024 May 30, 2025 May 8, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 7May 24May 42021: May 302022: May 232023: May 32024: May 302025: May 82026: May 11Fall at Hurley: chance of a frost before this dateFall, chance of a frost before the date: 10% September 13, 20% September 19, 30% September 22, 40% September 25, 50% September 28, 60% October 1, 70% October 3, 80% October 6, 90% October 11. Observed first fall frost in recent years: 2021 October 18, 2022 September 28, 2023 October 12, 2024 October 5, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 13Sep 28Oct 112021: October 182022: September 282023: October 122024: October 52025: October 8
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 30October 18
2022May 23September 28
2023May 3October 12
2024May 30October 5
2025May 8October 8
2026May 11season not over yet

What these dates mean

Setting out tender crops on the early spring date, May 4, is a gamble in Hurley because there is a 90 % chance of a light frost occurring later. The cautious date for planting tender varieties is June 7, when only a 10 % chance of a later frost remains.

The 50% date is May 24, marking the point at which a light frost is equally likely to occur later or not, while the 50% date is September 28 for the fall season. Gardeners who wish to finish harvesting tender crops with the lowest risk should aim for the cautious fall date, September 13, which carries only a 10 % chance of a frost having arrived earlier. The hard-frost median dates are May 8 in spring and October 8 in fall; a hard frost at 28°F can damage plant tissue more severely than 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 June 7" 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 13" 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 Hurley, WINumbered nearest stations: 1 — Ironwood, MI — 0 mi; 2 — Bergland Dam, MI — 32 mi; 3 — Madeline Island, WI — 35 mi; 4 — Winter, WI — 60 mi; 5 — Gordon, WI — 78 mi.WIMI25 mi · 40 km1. Ironwood, MI — 0 mi12. Bergland Dam, MI — 32 mi23. Madeline Island, WI — 35 mi34. Winter, WI — 60 mi45. Gordon, WI — 78 mi5
  1. Ironwood, MI 0 mi (1 km)
  2. Bergland Dam, MI 32 mi (51 km)
  3. Madeline Island, WI 35 mi (56 km)
  4. Winter, WI 60 mi (96 km)
  5. Gordon, WI 78 mi (126 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 46.4625, -90.1956.