U.S. Frost Dates by Weather Station

NOAA station USC00326365 · North Dakota

Frost Dates for New Salem, ND

NOAA weather station New Salem 5 NW (USC00326365), North Dakota · elevation 2150 ft (655 m) · hardiness zone 4a*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1850% chance of a frost after it
  • Typical first fall frostSeptember 2450% chance of a frost before it
  • Frost-free season127 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at New Salem, NDSpring: a frost after May 6 in 9 years out of 10, after May 18 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 12 in 1 year out of 10, before September 24 in half of the years, before October 6 in 9 years out of 10. Typical frost-free season: 127 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 18First frost ~Sep 24Frost season at New Salem, NDSpring: a frost after May 6 in 9 years out of 10, after May 18 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 12 in 1 year out of 10, before September 24 in half of the years, before October 6 in 9 years out of 10. Typical frost-free season: 127 days.JFMAMJJASONDLast frost ~May 18First frost ~Sep 24
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.Today

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 1September 12
50% (typical)May 18September 24
90% (likely)May 6October 6
Frost-free season (32°F, 50% chance)
127 days
Hard frost (28°F), last in spring, 50% chance after
May 8
Hard frost (28°F), first in fall, 50% chance before
October 3

The last 15 years (2006–2020 normals)

Typical last frost May 20 (2 days later than the 30-year normal), typical first fall frost September 27 (3 days later). Frost-free season 128 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 New Salem: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 27, 30% May 24, 40% May 21, 50% May 18, 60% May 16, 70% May 13, 80% May 10, 90% May 6. Observed last spring frost in recent years: 2021 May 11, 2022 June 3, 2023 May 2, 2024 May 4, 2025 May 21, 2026 May 10.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 18May 62021: May 112022: June 32023: May 22024: May 42025: May 212026: May 10Fall at New Salem: chance of a frost before this dateFall, chance of a frost before the date: 10% September 12, 20% September 17, 30% September 20, 40% September 22, 50% September 24, 60% September 27, 70% September 30, 80% October 2, 90% October 6. Observed first fall frost in recent years: 2021 September 25, 2022 October 7, 2023 October 6, 2024 September 22, 2025 September 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 12Sep 24Oct 62021: September 252022: October 72023: October 62024: September 222025: 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 11September 25
2022June 3October 7
2023May 2October 6
2024May 4September 22
2025May 21September 6
2026May 10season not over yet

What these dates mean

September 12 is the cautious fall date in New Salem for finishing the harvest, because only a 10 % chance of a light frost has occurred by then. In spring the cautious date for setting out tender crops is June 1, when the chance of a later light frost drops to 10 %. Both dates give gardeners a low-risk window for tender crops, while the earlier spring date of May 6 carries a 90 % chance of a frost and the later fall date of October 6 carries a 90 % chance of an earlier frost.

The 50 % dates mark the point at which a light frost is equally likely to have happened or not: May 18 in spring and September 24 in fall. The median hard-frost dates are May 8 and October 3; a hard frost at 28 °F can damage plants that survive a light frost at 32 °F, so it represents a more severe threat.

How to read the probabilities

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

  • Spring: "10% after June 1" 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 12" 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 New Salem, NDNumbered nearest stations: 1 — Heart Butte Dam, ND — 26 mi; 2 — Hebron, ND — 26 mi; 3 — Mandan, ND — 28 mi; 4 — Bismarck, ND — 35 mi; 5 — Richardton Abbey, ND — 39 mi.ND25 mi · 40 km1. Heart Butte Dam, ND — 26 mi12. Hebron, ND — 26 mi23. Mandan, ND — 28 mi34. Bismarck, ND — 35 mi45. Richardton Abbey, ND — 39 mi5
  1. Heart Butte Dam, ND 26 mi (41 km)
  2. Hebron, ND 26 mi (42 km)
  3. Mandan, ND 28 mi (45 km)
  4. Bismarck, ND 35 mi (57 km)
  5. Richardton Abbey, ND 39 mi (63 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: 46.8925, -101.4897.