U.S. Frost Dates by Weather Station

NOAA station USC00476330 · Wisconsin

Frost Dates for Oshkosh, WI

NOAA weather station Oshkosh (USC00476330), Wisconsin · elevation 750 ft (229 m) · hardiness zone 5b*

  • 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 2050% chance of a frost before it
  • Frost-free season178 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Oshkosh, WISpring: a frost after April 10 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 20 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 178 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 24First frost ~Oct 20Frost season at Oshkosh, WISpring: a frost after April 10 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 20 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 178 days.JFMAMJJASONDLast frost ~Apr 24First frost ~Oct 20
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 20
90% (likely)April 10November 2
Frost-free season (32°F, 50% chance)
178 days
Hard frost (28°F), last in spring, 50% chance after
April 13
Hard frost (28°F), first in fall, 50% chance before
October 31

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 23 (3 days later). Frost-free season 182 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 Oshkosh: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 8, 20% May 3, 30% April 30, 40% April 28, 50% April 24, 60% April 21, 70% April 18, 80% April 15, 90% April 10. Observed last spring frost in recent years: 2021 April 25, 2022 April 28, 2023 April 25, 2024 April 24, 2025 April 16, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 8Apr 24Apr 102021: April 252022: April 282023: April 252024: April 242025: April 162026: May 2Fall at Oshkosh: chance of a frost before this dateFall, chance of a frost before the date: 10% October 4, 20% October 9, 30% October 13, 40% October 17, 50% October 20, 60% October 23, 70% October 26, 80% October 30, 90% November 2. Observed first fall frost in recent years: 2021 October 25, 2022 October 15, 2023 October 30, 2024 October 24, 2025 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 4Oct 20Nov 22021: October 252022: October 152023: October 302024: October 242025: November 2
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 25October 25
2022April 28October 15
2023April 25October 30
2024April 24October 24
2025April 16November 2
2026May 2season not over yet

What these dates mean

The cautious fall date in Oshkosh for finishing the harvest is October 4, when there is only a 10 % chance that a light frost has arrived. In spring the cautious date for setting out tender crops is May 8, which carries a 10 % chance of a later frost, while planting on April 10 would be a gamble with a 90 % chance of frost later. Thus, a planting schedule that follows these cautious dates reduces the likelihood of frost damage.

The 50 % dates – April 24 for spring and October 20 for fall – mark the point of even odds for a light frost, giving gardeners a reference for average risk. The hard-frost 50 % dates are April 13 and October 31; a hard frost at 28 °F can damage or kill plants that survive a light frost, making it a more severe threat.

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 Oshkosh, WINumbered nearest stations: 1 — Fond du Lac, WI — 16 mi; 2 — Chilton, WI — 20 mi; 3 — New London, WI — 25 mi; 4 — Waupaca, WI — 34 mi; 5 — Plymouth, WI — 35 mi.WI25 mi · 40 km1. Fond du Lac, WI — 16 mi12. Chilton, WI — 20 mi23. New London, WI — 25 mi34. Waupaca, WI — 34 mi45. Plymouth, WI — 35 mi5
  1. Fond du Lac, WI 16 mi (26 km)
  2. Chilton, WI 20 mi (33 km)
  3. New London, WI 25 mi (40 km)
  4. Waupaca, WI 34 mi (55 km)
  5. Plymouth, WI 35 mi (57 km)

Sources

* Hardiness zone 5b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 44.0206, -88.5578.