U.S. Frost Dates by Weather Station

NOAA station USC00474894 · Wisconsin

Frost Dates for Luck, WI

NOAA weather station Luck (USC00474894), Wisconsin · elevation 1220 ft (372 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 20only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 450% chance of a frost before it
  • Frost-free season149 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Luck, WISpring: a frost after April 23 in 9 years out of 10, after May 6 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 4 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 149 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 4Frost season at Luck, WISpring: a frost after April 23 in 9 years out of 10, after May 6 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 4 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 149 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 4
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 20September 19
50% (typical)May 6October 4
90% (likely)April 23October 18
Frost-free season (32°F, 50% chance)
149 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 16

The last 15 years (2006–2020 normals)

Typical last frost May 4 (2 days earlier than the 30-year normal), typical first fall frost October 7 (3 days later). Frost-free season 154 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 Luck: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 20, 20% May 15, 30% May 12, 40% May 9, 50% May 6, 60% May 3, 70% April 30, 80% April 28, 90% April 23. Observed last spring frost in recent years: 2021 May 11, 2022 April 28, 2023 May 3, 2024 April 24, 2025 May 19, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 20May 6Apr 232021: May 112022: April 282023: May 32024: April 242025: May 192026: May 2Fall at Luck: chance of a frost before this dateFall, chance of a frost before the date: 10% September 19, 20% September 24, 30% September 28, 40% October 1, 50% October 4, 60% October 7, 70% October 10, 80% October 14, 90% October 18. Observed first fall frost in recent years: 2021 October 22, 2022 September 28, 2023 October 28, 2024 October 14, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 19Oct 4Oct 182021: October 222022: September 282023: October 282024: October 142025: 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 11October 22
2022April 28September 28
2023May 3October 28
2024April 24October 14
2025May 19October 8
2026May 2season not over yet

What these dates mean

May 20 is the cautious spring date in Luck, carrying only a 10 % chance that a light frost will occur later; it lets a gardener set out tender crops with minimal risk. The median point for spring light frost is May 6, which represents a 50 % chance of a frost later than this date. By contrast, April 23 carries a 90 % chance and is a gamble for early planting.

In the autumn the cautious date is September 19, with only a 10 % chance that a light frost has arrived earlier, marking the appropriate time to finish harvesting tender crops. The 50 % autumn median is October 4, indicating a 50 % chance of a frost earlier than this date, while October 18 is a gamble with a 90 % chance. Hard-frost risk is reflected by the 50 % dates of April 27 in spring and October 16 in fall; a hard frost damages plants more severely than a light frost because it reaches a lower temperature threshold.

How to read the probabilities

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

  • Spring: "10% after May 20" 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 19" 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 Luck, WINumbered nearest stations: 1 — Wild River State Park, MN — 13 mi; 2 — St. Croix Falls, WI — 14 mi; 3 — Grantsburg, WI — 17 mi; 4 — Amery, WI — 20 mi; 5 — Cumberland, WI — 23 mi.WIMN25 mi · 40 km1. Wild River State Park, MN — 13 mi12. St. Croix Falls, WI — 14 mi23. Grantsburg, WI — 17 mi34. Amery, WI — 20 mi45. Cumberland, WI — 23 mi5
  1. Wild River State Park, MN 13 mi (21 km)
  2. St. Croix Falls, WI 14 mi (22 km)
  3. Grantsburg, WI 17 mi (27 km)
  4. Amery, WI 20 mi (32 km)
  5. Cumberland, WI 23 mi (36 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: 45.5733, -92.4853.