U.S. Frost Dates by Weather Station

NOAA station USC00325638 · North Dakota

Frost Dates for Max, ND

NOAA weather station Max (USC00325638), North Dakota · elevation 2110 ft (643 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1050% chance of a frost after it
  • Typical first fall frostSeptember 2850% chance of a frost before it
  • Frost-free season141 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Max, NDSpring: a frost after April 29 in 9 years out of 10, after May 10 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 28 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 141 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 10First frost ~Sep 28Frost season at Max, NDSpring: a frost after April 29 in 9 years out of 10, after May 10 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 28 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 141 days.JFMAMJJASONDLast frost ~May 10First frost ~Sep 28
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 25September 15
50% (typical)May 10September 28
90% (likely)April 29October 11
Frost-free season (32°F, 50% chance)
141 days
Hard frost (28°F), last in spring, 50% chance after
May 2
Hard frost (28°F), first in fall, 50% chance before
October 6

The last 15 years (2006–2020 normals)

Typical last frost May 9 (1 day earlier than the 30-year normal), typical first fall frost October 2 (4 days later). Frost-free season 145 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 Max: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 19, 30% May 16, 40% May 13, 50% May 10, 60% May 8, 70% May 5, 80% May 3, 90% April 29. Observed last spring frost in recent years: 2021 May 11, 2022 May 21, 2023 May 2, 2024 April 27, 2025 May 17, 2026 May 9.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 10Apr 292021: May 112022: May 212023: May 22024: April 272025: May 172026: May 9Fall at Max: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 20, 30% September 23, 40% September 26, 50% September 28, 60% October 1, 70% October 3, 80% October 6, 90% October 11. Observed first fall frost in recent years: 2021 October 15, 2022 October 7, 2023 October 7, 2024 October 13, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 15Sep 28Oct 112021: October 152022: October 72023: October 72024: October 132025: 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 11October 15
2022May 21October 7
2023May 2October 7
2024April 27October 13
2025May 17October 6
2026May 9season not over yet

What these dates mean

In Max, North Dakota, the 32 °F 50% dates are May 10 and September 28, a span of 141 days that marks the period of even odds for a light frost. For a gardener, the May 10 date indicates a 50 % chance that a light frost could still occur later in spring, while the September 28 date indicates a 50 % chance that a light frost could be present by that point in the season. These dates are not frost thresholds themselves.

The cautious spring date is May 25, which carries only a 10 % chance of a light frost later and is therefore the low-risk point for setting out tender crops. In fall, the cautious date is September 15, with a 10 % chance of a light frost earlier, marking the low-risk moment to finish harvesting tender crops. A hard frost at 28 °F is more damaging than a light frost at 32 °F, so the median hard-frost dates of May 2 and October 6 are especially relevant.

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 15" 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 Max, NDNumbered nearest stations: 1 — Garrison, ND — 13 mi; 2 — near Minot, ND — 25 mi; 3 — Underwood, ND — 26 mi; 4 — Turtle Lake, ND — 28 mi; 5 — Minot (Airport), ND — 30 mi.25 mi · 40 km1. Garrison, ND — 13 mi12. near Minot, ND — 25 mi23. Underwood, ND — 26 mi34. Turtle Lake, ND — 28 mi45. Minot (Airport), ND — 30 mi5
  1. Garrison, ND 13 mi (21 km)
  2. near Minot, ND 25 mi (40 km)
  3. Underwood, ND 26 mi (42 km)
  4. Turtle Lake, ND 28 mi (45 km)
  5. Minot (Airport), ND 30 mi (48 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: 47.8214, -101.2922.