U.S. Frost Dates by Weather Station

NOAA station USC00219173 · Minnesota

Frost Dates for Wright, MN

NOAA weather station Wright 3 E (USC00219173), Minnesota · elevation 1330 ft (405 m) · hardiness zone 4a*

  • Lower-risk planting dateafter June 20only 1 spring in 10 still has a frost later
  • Typical last frostMay 3150% chance of a frost after it
  • Typical first fall frostSeptember 1850% chance of a frost before it
  • Frost-free season107 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Wright, MNSpring: a frost after May 15 in 9 years out of 10, after May 31 in half of the years, after June 20 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 18 in half of the years, before October 2 in 9 years out of 10. Typical frost-free season: 107 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 31First frost ~Sep 18Frost season at Wright, MNSpring: a frost after May 15 in 9 years out of 10, after May 31 in half of the years, after June 20 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 18 in half of the years, before October 2 in 9 years out of 10. Typical frost-free season: 107 days.JFMAMJJASONDLast frost ~May 31First frost ~Sep 18
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 20September 1
50% (typical)May 31September 18
90% (likely)May 15October 2
Frost-free season (32°F, 50% chance)
107 days
Hard frost (28°F), last in spring, 50% chance after
May 17
Hard frost (28°F), first in fall, 50% chance before
September 28

The last 15 years (2006–2020 normals)

Typical last frost May 26 (5 days earlier than the 30-year normal), typical first fall frost September 22 (4 days later). Frost-free season 117 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 Wright: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 20, 20% June 10, 30% June 5, 40% June 2, 50% May 31, 60% May 28, 70% May 25, 80% May 21, 90% May 15. Observed last spring frost in recent years: 2021 May 30, 2022 May 21, 2023 May 4, 2024 April 26, 2025 May 25, 2026 May 21.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jul 1Jun 20May 31May 152021: May 302022: May 212023: May 42024: April 262025: May 252026: May 21Fall at Wright: chance of a frost before this dateFall, chance of a frost before the date: 10% September 1, 20% September 7, 30% September 11, 40% September 15, 50% September 18, 60% September 21, 70% September 24, 80% September 27, 90% October 2. Observed first fall frost in recent years: 2021 October 16, 2022 September 27, 2023 October 9, 2024 October 4, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 1Sep 18Oct 22021: October 162022: September 272023: October 92024: 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 30October 16
2022May 21September 27
2023May 4October 9
2024April 26October 4
2025May 25October 8
2026May 21season not over yet

What these dates mean

June 20 marks the cautious spring date for setting out tender crops in Wright; with only a 10 % chance of a light frost later, a gardener can plan to transplant seedlings after that day with relatively low risk.

The median light-frost date, May 31, signals an even 50 % chance of frost later in spring, while the median fall date, September 18, carries an even 50 % chance of frost earlier; these dates give a balanced sense of when frost becomes as likely as not. The 50 % hard-frost dates are May 17 in spring and September 28 in fall, and a hard frost matters more than a light frost because 28 °F can injure plants that would survive a 32 °F event.

For a cautious fall plan, September 1 is the date to finish harvesting tender crops, as only a 10 % chance of a light frost has occurred earlier.

How to read the probabilities

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

  • Spring: "10% after June 20" 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 1" 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 Wright, MNNumbered nearest stations: 1 — Moose Lake, MN — 19 mi; 2 — Cloquet, MN — 20 mi; 3 — Floodwood, MN — 21 mi; 4 — Bruno, MN — 33 mi; 5 — Superior, WI — 42 mi.WI25 mi · 40 km1. Moose Lake, MN — 19 mi12. Cloquet, MN — 20 mi23. Floodwood, MN — 21 mi34. Bruno, MN — 33 mi45. Superior, WI — 42 mi5
  1. Moose Lake, MN 19 mi (31 km)
  2. Cloquet, MN 20 mi (33 km)
  3. Floodwood, MN 21 mi (33 km)
  4. Bruno, MN 33 mi (53 km)
  5. Superior, WI 42 mi (67 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: 46.6803, -92.9542.