U.S. Frost Dates by Weather Station

NOAA station USC00325993 · North Dakota

Frost Dates near Minot, ND

NOAA weather station Minot Experiment Station (USC00325993), North Dakota · elevation 1769 ft (539 m) · hardiness zone 4a*

Minot is the nearest town to the station (3.6 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 26only 1 spring in 10 still has a frost later
  • Typical last frostMay 1350% chance of a frost after it
  • Typical first fall frostSeptember 2750% chance of a frost before it
  • Frost-free season136 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season near Minot, NDSpring: a frost after May 1 in 9 years out of 10, after May 13 in half of the years, after May 26 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 9 in 9 years out of 10. Typical frost-free season: 136 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 13First frost ~Sep 27Frost season near Minot, NDSpring: a frost after May 1 in 9 years out of 10, after May 13 in half of the years, after May 26 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 9 in 9 years out of 10. Typical frost-free season: 136 days.JFMAMJJASONDLast frost ~May 13First 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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 26September 14
50% (typical)May 13September 27
90% (likely)May 1October 9
Frost-free season (32°F, 50% chance)
136 days
Hard frost (28°F), last in spring, 50% chance after
May 3
Hard frost (28°F), first in fall, 50% chance before
October 5

The last 15 years (2006–2020 normals)

Typical last frost May 10 (3 days earlier than the 30-year normal), typical first fall frost October 1 (4 days later). Frost-free season 143 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 Minot: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 26, 20% May 21, 30% May 18, 40% May 15, 50% May 13, 60% May 10, 70% May 7, 80% May 4, 90% May 1. Observed last spring frost in recent years: 2021 May 10, 2022 May 21, 2023 May 2, 2024 April 30, 2025 April 30, 2026 May 16.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 26May 13May 12021: May 102022: May 212023: May 22024: April 302025: April 302026: May 16Fall near Minot: chance of a frost before this dateFall, chance of a frost before the date: 10% September 14, 20% September 19, 30% September 22, 40% September 25, 50% September 27, 60% September 29, 70% October 2, 80% October 5, 90% October 9. Observed first fall frost in recent years: 2021 October 20, 2022 October 7, 2023 October 7, 2024 October 15, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 14Sep 27Oct 92021: October 202022: October 72023: October 72024: October 152025: October 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 10October 20
2022May 21October 7
2023May 2October 7
2024April 30October 15
2025April 30October 6
2026May 16season not over yet

What these dates mean

Setting out tender crops on May 1 is a gamble, because there is a 90% chance of a light frost later than this date in the Minot area.

The 50% dates, May 13 in spring and September 27 in fall, indicate the point at which a frost is equally likely to occur before or after. A cautious planting schedule would wait until May 26, when only a 10% chance of a later frost remains, and would finish tender-crop harvest by September 14, when the chance of an earlier frost is likewise 10%. The hard-frost 50% dates of May 3 and October 5 show when a 28 °F frost is equally likely to have occurred.

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 26" 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 Minot, NDNumbered nearest stations: 1 — Minot (Airport), ND — 5 mi; 2 — Max, ND — 25 mi; 3 — Garrison, ND — 37 mi; 4 — Upham, ND — 40 mi; 5 — Towner, ND — 44 mi.ND25 mi · 40 km1. Minot (Airport), ND — 5 mi12. Max, ND — 25 mi23. Garrison, ND — 37 mi34. Upham, ND — 40 mi45. Towner, ND — 44 mi5
  1. Minot (Airport), ND 5 mi (9 km)
  2. Max, ND 25 mi (40 km)
  3. Garrison, ND 37 mi (59 km)
  4. Upham, ND 40 mi (64 km)
  5. Towner, ND 44 mi (70 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: 48.1803, -101.2964.