U.S. Frost Dates by Weather Station

NOAA station USC00324013 · North Dakota

Frost Dates for Harvey, ND

NOAA weather station Harvey 4 NE (USC00324013), North Dakota · elevation 1611 ft (491 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1250% chance of a frost after it
  • Typical first fall frostSeptember 2650% chance of a frost before it
  • Frost-free season135 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Harvey, NDSpring: a frost after April 30 in 9 years out of 10, after May 12 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 26 in half of the years, before October 6 in 9 years out of 10. Typical frost-free season: 135 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 12First frost ~Sep 26Frost season at Harvey, NDSpring: a frost after April 30 in 9 years out of 10, after May 12 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 26 in half of the years, before October 6 in 9 years out of 10. Typical frost-free season: 135 days.JFMAMJJASONDLast frost ~May 12First frost ~Sep 26
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)May 25September 14
50% (typical)May 12September 26
90% (likely)April 30October 6
Frost-free season (32°F, 50% chance)
135 days
Hard frost (28°F), last in spring, 50% chance after
May 4
Hard frost (28°F), first in fall, 50% chance before
October 4

The last 15 years (2006–2020 normals)

Typical last frost May 11 (1 day earlier than the 30-year normal), typical first fall frost September 26. Frost-free season 136 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 Harvey: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 21, 30% May 17, 40% May 14, 50% May 12, 60% May 9, 70% May 7, 80% May 4, 90% April 30. Observed last spring frost in recent years: 2022 May 19, 2024 May 24, 2025 April 29, 2026 May 19.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 12Apr 302022: May 192024: May 242025: April 292026: May 19Fall at Harvey: chance of a frost before this dateFall, chance of a frost before the date: 10% September 14, 20% September 18, 30% September 21, 40% September 24, 50% September 26, 60% September 28, 70% October 1, 80% October 3, 90% October 6. Observed first fall frost in recent years: 2021 October 15, 2022 September 21, 2024 September 29, 2025 October 5.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 14Sep 26Oct 62021: October 152022: September 212024: September 292025: October 5
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
2021incomplete recordOctober 15
2022May 19September 21
2023incomplete recordincomplete record
2024May 24September 29
2025April 29October 5
2026May 19season not over yet

What these dates mean

The 135 days between the 32°F 50% dates, May 12 and September 26, define the window in which tender crops have the greatest chance of staying frost-free. The 50% date is May 12; there is a 50% chance of a frost later than this date, and the 50% date is September 26; there is a 50% chance of a frost earlier than this date. For a cautious spring plan, the date to set out tender crops is May 25, which carries only a 10% chance of a later frost. In the fall, the cautious date to finish harvesting tender crops is September 14, with only a 10% chance that a frost has arrived earlier. Hard frost at 28°F, marked by the median dates May 4 and October 4, can injure 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 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 Harvey, NDNumbered nearest stations: 1 — Drake, ND — 26 mi; 2 — McClusky, ND — 35 mi; 3 — Rugby, ND — 38 mi; 4 — Towner, ND — 46 mi; 5 — Turtle Lake, ND — 51 mi.25 mi · 40 km1. Drake, ND — 26 mi12. McClusky, ND — 35 mi23. Rugby, ND — 38 mi34. Towner, ND — 46 mi45. Turtle Lake, ND — 51 mi5
  1. Drake, ND 26 mi (42 km)
  2. McClusky, ND 35 mi (56 km)
  3. Rugby, ND 38 mi (61 km)
  4. Towner, ND 46 mi (73 km)
  5. Turtle Lake, ND 51 mi (82 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: 47.8083, -99.8758.