U.S. Frost Dates by Weather Station

NOAA station USC00324083 · North Dakota

Frost Dates for Hazelton, ND

NOAA weather station Hazelton 4 NW (USC00324083), North Dakota · elevation 1982 ft (604 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 27only 1 spring in 10 still has a frost later
  • Typical last frostMay 1250% 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 at Hazelton, NDSpring: a frost after May 2 in 9 years out of 10, after May 12 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 15 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: 136 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 12First frost ~Sep 27Frost season at Hazelton, NDSpring: a frost after May 2 in 9 years out of 10, after May 12 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 15 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: 136 days.JFMAMJJASONDLast frost ~May 12First 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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 27September 15
50% (typical)May 12September 27
90% (likely)May 2October 10
Frost-free season (32°F, 50% chance)
136 days
Hard frost (28°F), last in spring, 50% chance after
May 4
Hard frost (28°F), first in fall, 50% chance before
October 6

The last 15 years (2006–2020 normals)

Typical last frost May 13 (1 day later than the 30-year normal), typical first fall frost September 30 (3 days 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 at Hazelton: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 27, 20% May 21, 30% May 17, 40% May 15, 50% May 12, 60% May 10, 70% May 7, 80% May 5, 90% May 2. Observed last spring frost in recent years: 2021 May 28, 2022 May 21, 2023 May 3, 2024 May 5, 2025 May 18, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 12May 22021: May 282022: May 212023: May 32024: May 52025: May 182026: May 11Fall at Hazelton: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 19, 30% September 22, 40% September 24, 50% September 27, 60% September 29, 70% October 2, 80% October 5, 90% October 10. Observed first fall frost in recent years: 2021 October 21, 2022 September 22, 2023 October 7, 2024 October 7, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 15Sep 27Oct 102021: October 212022: September 222023: October 72024: October 72025: 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 28October 21
2022May 21September 22
2023May 3October 7
2024May 5October 7
2025May 18October 6
2026May 11season not over yet

What these dates mean

The cautious fall date for finishing the harvest in Hazelton is September 15, when there is only a 10 % chance that a light frost has already arrived.

For a gardener, the 50% date is May 12 and the 50% date is September 27, marking the point at which the odds of a light frost are even. The cautious spring date for setting out tender crops is May 27; the early spring date of May 2 carries a 90 % chance and is a gamble. The cautious fall date for finishing tender crops is September 15; the later fall date of October 10 carries a 90 % chance and is a gamble.

A hard frost at 28 °F, with median dates of May 4 in spring and October 6 in fall, can injure plants that would otherwise survive a light frost, so its timing is more critical.

How to read the probabilities

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

  • Spring: "10% after May 27" 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 Hazelton, NDNumbered nearest stations: 1 — Bismarck, ND — 26 mi; 2 — Napoleon, ND — 28 mi; 3 — Steele, ND — 32 mi; 4 — Mandan, ND — 33 mi; 5 — Pollock, SD — 43 mi.SD25 mi · 40 km1. Bismarck, ND — 26 mi12. Napoleon, ND — 28 mi23. Steele, ND — 32 mi34. Mandan, ND — 33 mi45. Pollock, SD — 43 mi5
  1. Bismarck, ND 26 mi (42 km)
  2. Napoleon, ND 28 mi (44 km)
  3. Steele, ND 32 mi (52 km)
  4. Mandan, ND 33 mi (54 km)
  5. Pollock, SD 43 mi (69 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: 46.5203, -100.3478.