U.S. Frost Dates by Weather Station

NOAA station USW00014837 · Wisconsin

Frost Dates for Madison (Madison-Dane Airport), WI

NOAA weather station Madison Dane Regional Airport (USW00014837), Wisconsin · elevation 866 ft (264 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 16only 1 spring in 10 still has a frost later
  • Typical last frostMay 150% chance of a frost after it
  • Typical first fall frostOctober 1050% chance of a frost before it
  • Frost-free season160 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Madison (Madison-Dane Airport), WISpring: a frost after April 16 in 9 years out of 10, after May 1 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 10 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 160 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 1First frost ~Oct 10Frost season at Madison (Madison-Dane Airport), WISpring: a frost after April 16 in 9 years out of 10, after May 1 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 10 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 160 days.JFMAMJJASONDLast frost ~May 1First frost ~Oct 10
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 16September 26
50% (typical)May 1October 10
90% (likely)April 16October 24
Frost-free season (32°F, 50% chance)
160 days
Hard frost (28°F), last in spring, 50% chance after
April 20
Hard frost (28°F), first in fall, 50% chance before
October 22

The last 15 years (2006–2020 normals)

Typical last frost April 30 (1 day earlier than the 30-year normal), typical first fall frost October 15 (5 days later). Frost-free season 166 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 Madison (Madison-Dane Airport): chance of a frost after this dateSpring, chance of a frost after the date: 10% May 16, 20% May 11, 30% May 7, 40% May 3, 50% May 1, 60% April 29, 70% April 25, 80% April 22, 90% April 16. Observed last spring frost in recent years: 2021 May 11, 2022 May 4, 2023 April 26, 2024 April 25, 2025 May 9, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1May 16May 1Apr 162021: May 112022: May 42023: April 262024: April 252025: May 92026: May 7Fall at Madison (Madison-Dane Airport): chance of a frost before this dateFall, chance of a frost before the date: 10% September 26, 20% September 30, 30% October 4, 40% October 7, 50% October 10, 60% October 12, 70% October 15, 80% October 18, 90% October 24. Observed first fall frost in recent years: 2021 October 22, 2022 October 15, 2023 October 17, 2024 October 16, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 26Oct 10Oct 242021: October 222022: October 152023: October 172024: October 162025: October 23
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
2022May 4October 15
2023April 26October 17
2024April 25October 16
2025May 9October 23
2026May 7season not over yet

What these dates mean

May 16 is the cautious spring date for Madison-Dane Airport, and it lets a gardener plan to set out tender crops with only a 10 % chance of a later light frost. The 50% spring date is May 1; there is a 50 % chance of a frost later than this date. In fall, September 26 is the cautious date to finish harvesting tender crops, carrying only a 10 % chance that a light frost has already arrived. The 50% fall date is October 10; there is a 50 % chance of a frost earlier than this date.

The median hard-frost dates are April 20 in spring and October 22 in fall; these mark the points where a 28 °F frost is equally likely to have occurred or not. A hard frost matters more because temperatures at 28 °F can injure plants that would survive a 32 °F light frost.

How to read the probabilities

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

  • Spring: "10% after May 16" 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 Madison (Madison-Dane Airport), WINumbered nearest stations: 1 — UW Arboretum - Madison, WI — 8 mi; 2 — Charmany Farm, WI — 9 mi; 3 — Arlington, WI — 11 mi; 4 — Portage, WI — 27 mi; 5 — Fort Atkinson, WI — 29 mi.IL25 mi · 40 km1. UW Arboretum - Madison, WI — 8 mi12. Charmany Farm, WI — 9 mi23. Arlington, WI — 11 mi34. Portage, WI — 27 mi45. Fort Atkinson, WI — 29 mi5
  1. UW Arboretum - Madison, WI 8 mi (13 km)
  2. Charmany Farm, WI 9 mi (14 km)
  3. Arlington, WI 11 mi (18 km)
  4. Portage, WI 27 mi (44 km)
  5. Fort Atkinson, WI 29 mi (47 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: 43.1406, -89.3453.