U.S. Frost Dates by Weather Station

NOAA station USC00211891 · Minnesota

Frost Dates near Crookston, MN

NOAA weather station Crookston NW Experiment Station (USC00211891), Minnesota · elevation 891 ft (272 m) · hardiness zone 4a*

Crookston is the nearest town to the station (3.1 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1150% chance of a frost after it
  • Typical first fall frostSeptember 2750% chance of a frost before it
  • Frost-free season138 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season near Crookston, MNSpring: a frost after April 28 in 9 years out of 10, after May 11 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before September 27 in half of the years, before October 10 in 9 years out of 10. Typical frost-free season: 138 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 11First frost ~Sep 27Frost season near Crookston, MNSpring: a frost after April 28 in 9 years out of 10, after May 11 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before September 27 in half of the years, before October 10 in 9 years out of 10. Typical frost-free season: 138 days.JFMAMJJASONDLast frost ~May 11First frost ~Sep 27
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 25September 14
50% (typical)May 11September 27
90% (likely)April 28October 10
Frost-free season (32°F, 50% chance)
138 days
Hard frost (28°F), last in spring, 50% chance after
May 1
Hard frost (28°F), first in fall, 50% chance before
October 7

The last 15 years (2006–2020 normals)

Typical last frost May 14 (3 days later than the 30-year normal), typical first fall frost September 28 (1 day later). Frost-free season 139 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 near Crookston: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 20, 30% May 16, 40% May 13, 50% May 11, 60% May 8, 70% May 5, 80% May 2, 90% April 28. Observed last spring frost in recent years: 2021 May 28, 2022 May 3, 2023 April 25, 2024 April 24, 2025 April 30, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 11Apr 282021: May 282022: May 32023: April 252024: April 242025: April 302026: May 11Fall near Crookston: chance of a frost before this dateFall, chance of a frost before the date: 10% September 14, 20% September 18, 30% September 22, 40% September 24, 50% September 27, 60% September 30, 70% October 3, 80% October 6, 90% October 10. Observed first fall frost in recent years: 2021 October 21, 2022 September 28, 2023 October 10, 2024 October 15, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 14Sep 27Oct 102021: October 212022: September 282023: October 102024: October 152025: 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 28October 21
2022May 3September 28
2023April 25October 10
2024April 24October 15
2025April 30October 8
2026May 11season not over yet

What these dates mean

September 14 is the cautious fall date for finishing the harvest of tender crops in the Crookston area. It carries only a 10 % chance that a light frost has arrived earlier, so planning around this date reduces the risk of frost damage at the end of the season.

For a gardener the 50 % dates are reference points: the 50 % date in spring is May 11, when there is a 50 % chance of a light frost later than this date, and the 50 % date in fall is September 27, when there is a 50 % chance of a light frost earlier than this date. A cautious spring plan uses the May 25 date, which has a 10 % chance of a frost later, while a cautious fall plan relies on the September 14 date. The hard-frost median dates are May 1 and October 7; a hard frost at 28 °F can injure or kill plants that survive a 32 °F light frost.

Because a hard frost reaches a lower temperature, it can cause more severe damage to plant tissues than a 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 25" 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 14" 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 Crookston, MNNumbered nearest stations: 1 — Red Lake Falls, MN — 16 mi; 2 — near Grand Forks, ND — 24 mi; 3 — Grand Forks (Airport), ND — 28 mi; 4 — Argyle, MN — 37 mi; 5 — Georgetown, MN — 52 mi.MNND25 mi · 40 km1. Red Lake Falls, MN — 16 mi12. near Grand Forks, ND — 24 mi23. Grand Forks (Airport), ND — 28 mi34. Argyle, MN — 37 mi45. Georgetown, MN — 52 mi5
  1. Red Lake Falls, MN 16 mi (26 km)
  2. near Grand Forks, ND 24 mi (38 km)
  3. Grand Forks (Airport), ND 28 mi (45 km)
  4. Argyle, MN 37 mi (59 km)
  5. Georgetown, MN 52 mi (83 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: 47.8186, -96.6139.