U.S. Frost Dates by Weather Station

NOAA station USW00014918 · Minnesota

Frost Dates near International Falls, MN

NOAA weather station International Falls International Airport (USW00014918), Minnesota · elevation 1183 ft (361 m) · hardiness zone 3b*

International Falls is the nearest town to the station (2.8 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 June 16only 1 spring in 10 still has a frost later
  • Typical last frostMay 2950% chance of a frost after it
  • Typical first fall frostSeptember 1350% chance of a frost before it
  • Frost-free season109 daystypical year, 32°F
  • Hardiness zone3bcalculated*

The year at a glance

Frost season near International Falls, MNSpring: a frost after May 13 in 9 years out of 10, after May 29 in half of the years, after June 16 in 1 year out of 10. Fall: the first frost comes before August 30 in 1 year out of 10, before September 13 in half of the years, before September 28 in 9 years out of 10. Typical frost-free season: 109 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 29First frost ~Sep 13Frost season near International Falls, MNSpring: a frost after May 13 in 9 years out of 10, after May 29 in half of the years, after June 16 in 1 year out of 10. Fall: the first frost comes before August 30 in 1 year out of 10, before September 13 in half of the years, before September 28 in 9 years out of 10. Typical frost-free season: 109 days.JFMAMJJASONDLast frost ~May 29First frost ~Sep 13
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)June 16August 30
50% (typical)May 29September 13
90% (likely)May 13September 28
Frost-free season (32°F, 50% chance)
109 days
Hard frost (28°F), last in spring, 50% chance after
May 14
Hard frost (28°F), first in fall, 50% chance before
September 26

The last 15 years (2006–2020 normals)

Typical last frost May 29 (same as the 30-year normal), typical first fall frost September 13. Frost-free season 109 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 International Falls: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 16, 20% June 8, 30% June 4, 40% June 1, 50% May 29, 60% May 26, 70% May 22, 80% May 18, 90% May 13. Observed last spring frost in recent years: 2021 May 29, 2022 May 23, 2023 May 3, 2024 May 26, 2025 May 24, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 16May 29May 132021: May 292022: May 232023: May 32024: May 262025: May 242026: May 20Fall near International Falls: chance of a frost before this dateFall, chance of a frost before the date: 10% August 30, 20% September 3, 30% September 6, 40% September 10, 50% September 13, 60% September 17, 70% September 20, 80% September 24, 90% September 28. Observed first fall frost in recent years: 2021 October 17, 2022 September 27, 2023 September 13, 2024 September 7, 2025 September 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Aug 30Sep 13Sep 282021: October 172022: September 272023: September 132024: September 72025: September 6
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 17
2022May 23September 27
2023May 3September 13
2024May 26September 7
2025May 24September 6
2026May 20season not over yet

What these dates mean

June 16 is the cautious spring light-frost date for the International Falls area; with only a 10 % chance of a frost later than that day, a gardener can plan to set out tender crops after it. The 50 % median date in spring is May 29, which simply marks the point where the chance of a frost is even; it is not a frost date. Likewise, the fall 50 % median date is September 13.

The cautious fall light-frost date is August 30, when there is only a 10 % chance that a frost has arrived earlier, so finishing harvest of tender crops before then keeps risk low. The 50 % median dates for hard frost are May 14 in spring and September 26 in fall; a hard frost at 28 °F can damage or kill plants that survive a light frost, making it a more critical threshold.

How to read the probabilities

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

  • Spring: "10% after June 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 August 30" 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 International Falls, MNNumbered nearest stations: 1 — near Hibbing, MN — 85 mi; 2 — Eveleth, MN — 86 mi; 3 — Thorhult, MN — 88 mi; 4 — near Grand Rapids, MN — 91 mi; 5 — Leech Lake, MN — 99 mi.MN25 mi · 40 km1. near Hibbing, MN — 85 mi12. Eveleth, MN — 86 mi23. Thorhult, MN — 88 mi34. near Grand Rapids, MN — 91 mi45. Leech Lake, MN — 99 mi5
  1. near Hibbing, MN 85 mi (137 km)
  2. Eveleth, MN 86 mi (139 km)
  3. Thorhult, MN 88 mi (142 km)
  4. near Grand Rapids, MN 91 mi (147 km)
  5. Leech Lake, MN 99 mi (159 km)

Sources

* Hardiness zone 3b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 48.5614, -93.3981.