U.S. Frost Dates by Weather Station

NOAA station USC00477349 · Wisconsin

Frost Dates for Rosholt, WI

NOAA weather station Rosholt 9 NNE (USC00477349), Wisconsin · elevation 1183 ft (361 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 21only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 550% chance of a frost before it
  • Frost-free season150 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Rosholt, WISpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 21 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 5 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 150 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 5Frost season at Rosholt, WISpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 21 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 5 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 150 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 5
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.Today

Frost dates (32°F)

Probability of frost, based on 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 21September 22
50% (typical)May 6October 5
90% (likely)April 24October 20
Frost-free season (32°F, 50% chance)
150 days
Hard frost (28°F), last in spring, 50% chance after
April 26
Hard frost (28°F), first in fall, 50% chance before
October 17

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 11 (6 days later). Frost-free season 157 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 Rosholt: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 21, 20% May 16, 30% May 12, 40% May 9, 50% May 6, 60% May 3, 70% April 30, 80% April 28, 90% April 24. Observed last spring frost in recent years: 2021 May 28, 2022 May 5, 2023 May 3, 2024 April 26, 2025 May 10.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 21May 6Apr 242021: May 282022: May 52023: May 32024: April 262025: May 10Fall at Rosholt: chance of a frost before this dateFall, chance of a frost before the date: 10% September 22, 20% September 27, 30% September 30, 40% October 2, 50% October 5, 60% October 8, 70% October 11, 80% October 15, 90% October 20. Observed first fall frost in recent years: 2021 October 22, 2022 September 29, 2023 October 7.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 22Oct 5Oct 202021: October 222022: September 292023: October 7
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 28October 22
2022May 5September 29
2023May 3October 7
2024April 26incomplete record
2025May 10incomplete record
2026no dataseason not over yet

What these dates mean

Setting out tender crops on the early spring date of April 24 in Rosholt carries a 90% chance of a light frost, making it a gamble. A cautious plan waits until the May 21 date, which has only a 10% chance of a light frost later.

The 50% date of May 6 means there is an even chance of a light frost occurring after this day, while the median hard-frost date, April 26, indicates an even chance of a hard frost later in spring. In fall, the 50% date of October 5 and the median hard-frost date, October 17, similarly mark the points where the odds are split. For a cautious fall schedule, September 22 is used, with only a 10% chance that a light frost has arrived earlier.

Hard frost at 28 °F can damage or kill plants that survive a light frost at 32 °F, so it is a more serious 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 21" 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 22" 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 Rosholt, WINumbered nearest stations: 1 — near Wausau, WI — 22 mi; 2 — Stevens Point, WI — 24 mi; 3 — Clintonville, WI — 26 mi; 4 — Waupaca, WI — 29 mi; 5 — Shawano, WI — 31 mi.WI25 mi · 40 km1. near Wausau, WI — 22 mi12. Stevens Point, WI — 24 mi23. Clintonville, WI — 26 mi34. Waupaca, WI — 29 mi45. Shawano, WI — 31 mi5
  1. near Wausau, WI 22 mi (36 km)
  2. Stevens Point, WI 24 mi (38 km)
  3. Clintonville, WI 26 mi (42 km)
  4. Waupaca, WI 29 mi (46 km)
  5. Shawano, WI 31 mi (50 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: 44.7511, -89.245.