U.S. Frost Dates by Weather Station

NOAA station USW00014919 · North Dakota

Frost Dates for Jamestown, ND

NOAA weather station Jamestown Municipal Airport (USW00014919), North Dakota · elevation 1494 ft (455 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 24only 1 spring in 10 still has a frost later
  • Typical last frostMay 1150% chance of a frost after it
  • Typical first fall frostSeptember 2850% chance of a frost before it
  • Frost-free season138 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Jamestown, NDSpring: a frost after April 28 in 9 years out of 10, after May 11 in half of the years, after May 24 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 9 in 9 years out of 10. Typical frost-free season: 138 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 11First frost ~Sep 28Frost season at Jamestown, NDSpring: a frost after April 28 in 9 years out of 10, after May 11 in half of the years, after May 24 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 9 in 9 years out of 10. Typical frost-free season: 138 days.JFMAMJJASONDLast frost ~May 11First 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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 24September 15
50% (typical)May 11September 28
90% (likely)April 28October 9
Frost-free season (32°F, 50% chance)
138 days
Hard frost (28°F), last in spring, 50% chance after
May 1
Hard frost (28°F), first in fall, 50% chance before
October 6

The last 15 years (2006–2020 normals)

Typical last frost May 11 (same as the 30-year normal), typical first fall frost September 30 (2 days later). Frost-free season 141 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 Jamestown: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 24, 20% May 19, 30% May 16, 40% May 13, 50% May 11, 60% May 8, 70% May 5, 80% May 2, 90% April 28. Observed last spring frost in recent years: 2021 May 28, 2022 April 28, 2023 May 2, 2024 May 5, 2025 April 29, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 24May 11Apr 282021: May 282022: April 282023: May 22024: May 52025: April 292026: May 20Fall at Jamestown: 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% September 30, 70% October 2, 80% October 5, 90% October 9. Observed first fall frost in recent years: 2021 October 20, 2022 September 28, 2023 October 6, 2024 October 14, 2025 October 13.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 15Sep 28Oct 92021: October 202022: September 282023: October 62024: October 142025: October 13
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 20
2022April 28September 28
2023May 2October 6
2024May 5October 14
2025April 29October 13
2026May 20season not over yet

What these dates mean

May 24, with a 10 % chance of a frost later, is the cautious date for setting out tender crops in Jamestown, allowing a gardener to begin planting when the risk of a light frost is low.

The 50 % date is May 11, a 50 % chance of a frost later than this date, and the 50 % date is September 28, a 50 % chance of a frost earlier than this date; these median dates mark the point at which a light frost is as likely as not. The hard-frost 50 % dates are May 1 and October 6; a hard frost can damage plants that survive a light frost.

September 15, with a 10 % chance of a frost earlier, is the cautious date to finish harvesting tender crops, indicating that the likelihood of a light frost before that day remains low.

How to read the probabilities

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

  • Spring: "10% after May 24" 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 Jamestown, NDNumbered nearest stations: 1 — Jamestown State Hosp, ND — 3 mi; 2 — Streeter, ND — 40 mi; 3 — McHenry, ND — 45 mi; 4 — Fullerton, ND — 55 mi; 5 — Napoleon, ND — 60 mi.ND25 mi · 40 km1. Jamestown State Hosp, ND — 3 mi12. Streeter, ND — 40 mi23. McHenry, ND — 45 mi34. Fullerton, ND — 55 mi45. Napoleon, ND — 60 mi5
  1. Jamestown State Hosp, ND 3 mi (5 km)
  2. Streeter, ND 40 mi (64 km)
  3. McHenry, ND 45 mi (73 km)
  4. Fullerton, ND 55 mi (88 km)
  5. Napoleon, ND 60 mi (96 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 46.9258, -98.6692.