U.S. Frost Dates by Weather Station

NOAA station USC00476922 · Wisconsin

Frost Dates for Racine, WI

NOAA weather station Racine (USC00476922), Wisconsin · elevation 595 ft (181 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 6only 1 spring in 10 still has a frost later
  • Typical last frostApril 2050% chance of a frost after it
  • Typical first fall frostOctober 2450% chance of a frost before it
  • Frost-free season184 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Racine, WISpring: a frost after April 7 in 9 years out of 10, after April 20 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 24 in half of the years, before November 5 in 9 years out of 10. Typical frost-free season: 184 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 20First frost ~Oct 24Frost season at Racine, WISpring: a frost after April 7 in 9 years out of 10, after April 20 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 24 in half of the years, before November 5 in 9 years out of 10. Typical frost-free season: 184 days.JFMAMJJASONDLast frost ~Apr 20First frost ~Oct 24
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 6October 8
50% (typical)April 20October 24
90% (likely)April 7November 5
Frost-free season (32°F, 50% chance)
184 days
Hard frost (28°F), last in spring, 50% chance after
April 9
Hard frost (28°F), first in fall, 50% chance before
November 3

The last 15 years (2006–2020 normals)

Typical last frost April 21 (1 day later than the 30-year normal), typical first fall frost October 25 (1 day later). Frost-free season 183 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 Racine: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 6, 20% May 1, 30% April 27, 40% April 23, 50% April 20, 60% April 17, 70% April 15, 80% April 11, 90% April 7. Observed last spring frost in recent years: 2021 April 22, 2022 May 9, 2023 April 18, 2024 April 25, 2025 April 9, 2026 April 8.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 6Apr 20Apr 72021: April 222022: May 92023: April 182024: April 252025: April 92026: April 8Fall at Racine: chance of a frost before this dateFall, chance of a frost before the date: 10% October 8, 20% October 15, 30% October 18, 40% October 21, 50% October 24, 60% October 27, 70% October 30, 80% November 1, 90% November 5. Observed first fall frost in recent years: 2021 November 1, 2022 October 8, 2023 October 30, 2024 November 21, 2025 November 9.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 8Oct 24Nov 52021: November 12022: October 82023: October 302024: November 212025: November 9
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 1
2022May 9October 8
2023April 18October 30
2024April 25November 21
2025April 9November 9
2026April 8season not over yet

What these dates mean

May 6 is the cautious spring date in Racine, allowing a gardener to set out tender crops with only a 10% chance that a light frost will occur later. Planting before April 7 would be a gamble, as that date has a 90% chance of a frost.

The 50% dates mark the median point of frost risk: April 20 in spring and October 24 in fall each represent an even odds (50% chance) of a light frost occurring later or earlier, respectively. For a low-risk schedule, the cautious spring date is May 6 and the cautious fall date is October 8, each carrying only a 10% chance of frost on the opposite side of the season.

A hard frost at 28°F, such as the median dates April 9 and November 3, can damage plants 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 May 6" 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 8" 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 Racine, WINumbered nearest stations: 1 — Kenosha, WI — 10 mi; 2 — near Milwaukee, WI — 18 mi; 3 — Burlington, WI — 24 mi; 4 — near Wauwatosa, WI — 28 mi; 5 — near McHenry, IL — 36 mi.WIILMI25 mi · 40 km1. Kenosha, WI — 10 mi12. near Milwaukee, WI — 18 mi23. Burlington, WI — 24 mi34. near Wauwatosa, WI — 28 mi45. near McHenry, IL — 36 mi5
  1. Kenosha, WI 10 mi (16 km)
  2. near Milwaukee, WI 18 mi (30 km)
  3. Burlington, WI 24 mi (39 km)
  4. near Wauwatosa, WI 28 mi (46 km)
  5. near McHenry, IL 36 mi (58 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.7022, -87.7861.