U.S. Frost Dates by Weather Station

NOAA station USC00214994 · Minnesota

Frost Dates for Madison, MN

NOAA weather station Madison WWTP (USC00214994), Minnesota · elevation 1075 ft (328 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostMay 350% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season151 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Madison, MNSpring: a frost after April 21 in 9 years out of 10, after May 3 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 2 in half of the years, before October 15 in 9 years out of 10. Typical frost-free season: 151 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 3First frost ~Oct 2Frost season at Madison, MNSpring: a frost after April 21 in 9 years out of 10, after May 3 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 2 in half of the years, before October 15 in 9 years out of 10. Typical frost-free season: 151 days.JFMAMJJASONDLast frost ~May 3First frost ~Oct 2
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15September 20
50% (typical)May 3October 2
90% (likely)April 21October 15
Frost-free season (32°F, 50% chance)
151 days
Hard frost (28°F), last in spring, 50% chance after
April 23
Hard frost (28°F), first in fall, 50% chance before
October 12

The last 15 years (2006–2020 normals)

Typical last frost May 4 (1 day later than the 30-year normal), typical first fall frost October 6 (4 days later). Frost-free season 152 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: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 11, 30% May 7, 40% May 5, 50% May 3, 60% May 1, 70% April 29, 80% April 25, 90% April 21. Observed last spring frost in recent years: 2021 May 11, 2022 April 28, 2023 May 3, 2024 April 24, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1May 15May 3Apr 212021: May 112022: April 282023: May 32024: April 242026: May 11Fall at Madison: chance of a frost before this dateFall, chance of a frost before the date: 10% September 20, 20% September 25, 30% September 28, 40% September 30, 50% October 2, 60% October 5, 70% October 8, 80% October 11, 90% October 15. Observed first fall frost in recent years: 2021 October 16, 2022 September 27, 2023 October 7, 2024 October 4, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 20Oct 2Oct 152021: October 162022: September 272023: October 72024: October 42025: October 8
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 16
2022April 28September 27
2023May 3October 7
2024April 24October 4
2025incomplete recordOctober 8
2026May 11season not over yet

What these dates mean

May 15 is the cautious spring date in Madison, marking the point when a gardener can set out tender crops with only a 10% chance of a later light frost. The 50% date is May 3; at this date there is an even chance of a light frost later in spring. September 20 is the cautious fall date, allowing a gardener to finish harvesting tender crops with only a 10% chance that a light frost has already arrived. The 50% date is October 2; here there is an even chance of a light frost earlier in fall.

Hard-frost dates are April 23 in spring and October 12 in fall, and a hard frost at 28 °F 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 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 20" 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, MNNumbered nearest stations: 1 — Milan, MN — 14 mi; 2 — Canby, MN — 20 mi; 3 — Artichoke Lake 1 E, MN — 27 mi; 4 — Clear Lake, SD — 30 mi; 5 — Benson, MN — 34 mi.MNSD25 mi · 40 km1. Milan, MN — 14 mi12. Canby, MN — 20 mi23. Artichoke Lake 1 E, MN — 27 mi34. Clear Lake, SD — 30 mi45. Benson, MN — 34 mi5
  1. Milan, MN 14 mi (23 km)
  2. Canby, MN 20 mi (33 km)
  3. Artichoke Lake 1 E, MN 27 mi (43 km)
  4. Clear Lake, SD 30 mi (49 km)
  5. Benson, MN 34 mi (55 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: 45.0022, -96.1661.