U.S. Frost Dates by Weather Station

NOAA station USC00475178 · Wisconsin

Frost Dates for Mauston, WI

NOAA weather station Mauston 1 SE (USC00475178), Wisconsin · elevation 865 ft (264 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostMay 250% chance of a frost after it
  • Typical first fall frostOctober 750% chance of a frost before it
  • Frost-free season158 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Mauston, WISpring: a frost after April 19 in 9 years out of 10, after May 2 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 7 in half of the years, before October 21 in 9 years out of 10. Typical frost-free season: 158 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 2First frost ~Oct 7Frost season at Mauston, WISpring: a frost after April 19 in 9 years out of 10, after May 2 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 7 in half of the years, before October 21 in 9 years out of 10. Typical frost-free season: 158 days.JFMAMJJASONDLast frost ~May 2First frost ~Oct 7
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15September 26
50% (typical)May 2October 7
90% (likely)April 19October 21
Frost-free season (32°F, 50% chance)
158 days
Hard frost (28°F), last in spring, 50% chance after
April 21
Hard frost (28°F), first in fall, 50% chance before
October 19

The last 15 years (2006–2020 normals)

Typical last frost May 2 (same as the 30-year normal), typical first fall frost October 11 (4 days later). Frost-free season 161 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 Mauston: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 10, 30% May 7, 40% May 4, 50% May 2, 60% April 30, 70% April 27, 80% April 24, 90% April 19. Observed last spring frost in recent years: 2021 May 12, 2022 May 5, 2023 April 27, 2024 April 25, 2025 May 9, 2026 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1May 15May 2Apr 192021: May 122022: May 52023: April 272024: April 252025: May 92026: May 12Fall at Mauston: chance of a frost before this dateFall, chance of a frost before the date: 10% September 26, 20% September 30, 30% October 2, 40% October 5, 50% October 7, 60% October 10, 70% October 13, 80% October 16, 90% October 21. Observed first fall frost in recent years: 2021 October 22, 2022 October 8, 2023 October 17, 2024 October 15, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 26Oct 7Oct 212021: October 222022: October 82023: October 172024: October 152025: October 24
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 12October 22
2022May 5October 8
2023April 27October 17
2024April 25October 15
2025May 9October 24
2026May 12season not over yet

What these dates mean

The cautious fall date in Mauston for finishing the harvest is September 26, 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 15, which carries a 10 % chance of a light frost later in the season.

The 50% date is May 2, indicating an even-odds chance of a light frost later in the season, while the 50% date is October 7, indicating an even-odds chance of a light frost earlier. Gardeners who prefer the lower-risk option would aim for the May 15 date in spring and the September 26 date in fall, accepting the small probability of frost in order to protect sensitive plants.

A hard frost at 28 °F can damage or kill tender vegetation more readily 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 15" 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 26" 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 Mauston, WINumbered nearest stations: 1 — Wisconsin Dells, WI — 19 mi; 2 — Mather, WI — 30 mi; 3 — Hancock Experiment Farm, WI — 35 mi; 4 — Portage, WI — 36 mi; 5 — Montello, WI — 37 mi.WI25 mi · 40 km1. Wisconsin Dells, WI — 19 mi12. Mather, WI — 30 mi23. Hancock Experiment Farm, WI — 35 mi34. Portage, WI — 36 mi45. Montello, WI — 37 mi5
  1. Wisconsin Dells, WI 19 mi (31 km)
  2. Mather, WI 30 mi (49 km)
  3. Hancock Experiment Farm, WI 35 mi (56 km)
  4. Portage, WI 36 mi (58 km)
  5. Montello, WI 37 mi (60 km)

Sources

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

Station coordinates: 43.79, -90.0597.