U.S. Frost Dates by Weather Station

NOAA station USC00219134 · Minnesota

Frost Dates for Wolf Ridge Elc, MN

NOAA weather station Wolf Ridge Elc (USC00219134), Minnesota · elevation 1400 ft (427 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 31only 1 spring in 10 still has a frost later
  • Typical last frostMay 1550% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season137 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Wolf Ridge Elc, MNSpring: a frost after April 30 in 9 years out of 10, after May 15 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 17 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 137 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 15First frost ~Oct 1Frost season at Wolf Ridge Elc, MNSpring: a frost after April 30 in 9 years out of 10, after May 15 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 17 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 137 days.JFMAMJJASONDLast frost ~May 15First frost ~Oct 1
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 31September 17
50% (typical)May 15October 1
90% (likely)April 30October 14
Frost-free season (32°F, 50% chance)
137 days
Hard frost (28°F), last in spring, 50% chance after
May 2
Hard frost (28°F), first in fall, 50% chance before
October 10

The last 15 years (2006–2020 normals)

Typical last frost May 14 (1 day earlier than the 30-year normal), typical first fall frost October 3 (2 days later). Frost-free season 141 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 Wolf Ridge Elc: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 31, 20% May 26, 30% May 22, 40% May 19, 50% May 15, 60% May 11, 70% May 7, 80% May 4, 90% April 30. Observed last spring frost in recent years: 2021 May 29, 2022 May 5, 2023 May 3, 2024 May 10, 2025 May 19, 2026 May 21.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 31May 15Apr 302021: May 292022: May 52023: May 32024: May 102025: May 192026: May 21Fall at Wolf Ridge Elc: chance of a frost before this dateFall, chance of a frost before the date: 10% September 17, 20% September 21, 30% September 25, 40% September 28, 50% October 1, 60% October 3, 70% October 5, 80% October 8, 90% October 14. Observed first fall frost in recent years: 2021 October 21, 2023 October 7, 2024 October 10, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 17Oct 1Oct 142021: October 212023: October 72024: October 102025: 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 29October 21
2022May 5incomplete record
2023May 3October 7
2024May 10October 10
2025May 19October 8
2026May 21season not over yet

What these dates mean

May 31 is the cautious spring date for light frost (32 °F) in Wolf Ridge Elc, and it lets a gardener plan to set out tender crops with only a 10 % chance of a later frost.

The 50% spring date, May 15, indicates a 50 % chance of a light frost later, while the 50% fall date, October 1, indicates a 50 % chance of a light frost earlier. For a cautious fall schedule, September 17 is the date that carries a 10 % chance of an earlier frost, allowing harvest of tender crops. The 27-year record provides the basis for these probabilities.

Hard frost (28 °F) dates are May 2 in spring and October 10 in fall; a hard frost can damage or kill 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 31" 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 17" 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 Wolf Ridge Elc, MNNumbered nearest stations: 1 — Two Harbors, MN — 36 mi; 2 — Grand Marais, MN — 46 mi; 3 — Madeline Island, WI — 51 mi; 4 — Eveleth, MN — 61 mi; 5 — Superior, WI — 64 mi.MNWI25 mi · 40 km1. Two Harbors, MN — 36 mi12. Grand Marais, MN — 46 mi23. Madeline Island, WI — 51 mi34. Eveleth, MN — 61 mi45. Superior, WI — 64 mi5
  1. Two Harbors, MN 36 mi (58 km)
  2. Grand Marais, MN 46 mi (75 km)
  3. Madeline Island, WI 51 mi (82 km)
  4. Eveleth, MN 61 mi (99 km)
  5. Superior, WI 64 mi (103 km)

Sources

* Hardiness zone 4a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 47.45, -91.2167.