U.S. Frost Dates by Weather Station

NOAA station USC00321871 · North Dakota

Frost Dates for Crosby, ND

NOAA weather station Crosby (USC00321871), North Dakota · elevation 1959 ft (597 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 28only 1 spring in 10 still has a frost later
  • Typical last frostMay 1750% chance of a frost after it
  • Typical first fall frostSeptember 2350% chance of a frost before it
  • Frost-free season128 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Crosby, NDSpring: a frost after May 6 in 9 years out of 10, after May 17 in half of the years, after May 28 in 1 year out of 10. Fall: the first frost comes before September 11 in 1 year out of 10, before September 23 in half of the years, before October 4 in 9 years out of 10. Typical frost-free season: 128 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 17First frost ~Sep 23Frost season at Crosby, NDSpring: a frost after May 6 in 9 years out of 10, after May 17 in half of the years, after May 28 in 1 year out of 10. Fall: the first frost comes before September 11 in 1 year out of 10, before September 23 in half of the years, before October 4 in 9 years out of 10. Typical frost-free season: 128 days.JFMAMJJASONDLast frost ~May 17First frost ~Sep 23
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 28September 11
50% (typical)May 17September 23
90% (likely)May 6October 4
Frost-free season (32°F, 50% chance)
128 days
Hard frost (28°F), last in spring, 50% chance after
May 7
Hard frost (28°F), first in fall, 50% chance before
September 30

The last 15 years (2006–2020 normals)

Typical last frost May 16 (1 day earlier than the 30-year normal), typical first fall frost September 25 (2 days later). Frost-free season 133 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 Crosby: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 28, 20% May 24, 30% May 22, 40% May 19, 50% May 17, 60% May 15, 70% May 12, 80% May 10, 90% May 6. Observed last spring frost in recent years: 2021 May 10, 2022 May 21.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 28May 17May 62021: May 102022: May 21Fall at Crosby: chance of a frost before this dateFall, chance of a frost before the date: 10% September 11, 20% September 16, 30% September 19, 40% September 21, 50% September 23, 60% September 25, 70% September 27, 80% September 30, 90% October 4. Observed first fall frost in recent years: 2021 October 13, 2022 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 11Sep 23Oct 42021: October 132022: 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 10October 13
2022May 21October 6
2023incomplete recordno data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

May 28 is the cautious spring light-frost date for Crosby. With only a 10% chance of a frost later than this day, a gardener can plan to set out tender crops knowing the likelihood of a light frost is low. The 50% date, May 17, is the median point where the chance of a frost later is even; it is not itself a frost threshold.

In the fall the cautious date is September 11, when there is a 10% chance that a frost has already arrived, allowing a gardener to finish harvesting tender crops with minimal risk. The median point for fall light frost is September 23, the 50% date. The hard-frost median dates are May 7 in spring and September 30 in fall, and a hard frost matters more than a light frost because temperatures of 28 °F can damage plant tissue that survives a 32 °F frost.

How to read the probabilities

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

  • Spring: "10% after May 28" 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 11" 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 Crosby, NDNumbered nearest stations: 1 — Fortuna, ND — 23 mi; 2 — Westby, MT — 34 mi; 3 — Williston (Sloulin Airport), ND — 53 mi; 4 — Kenmare, ND — 57 mi; 5 — near Williston, ND — 57 mi.NDMT25 mi · 40 km1. Fortuna, ND — 23 mi12. Westby, MT — 34 mi23. Williston (Sloulin Airport), ND — 53 mi34. Kenmare, ND — 57 mi45. near Williston, ND — 57 mi5
  1. Fortuna, ND 23 mi (37 km)
  2. Westby, MT 34 mi (55 km)
  3. Williston (Sloulin Airport), ND 53 mi (86 km)
  4. Kenmare, ND 57 mi (92 km)
  5. near Williston, ND 57 mi (92 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: 48.9144, -103.2978.