U.S. Frost Dates by Weather Station

NOAA station USC00321435 · North Dakota

Frost Dates for Cavalier, ND

NOAA weather station Cavalier 7 NW (USC00321435), North Dakota · elevation 899 ft (274 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 3050% chance of a frost before it
  • Frost-free season139 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Cavalier, NDSpring: a frost after April 29 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 17 in 1 year out of 10, before September 30 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 139 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 12First frost ~Sep 30Frost season at Cavalier, NDSpring: a frost after April 29 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 17 in 1 year out of 10, before September 30 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 139 days.JFMAMJJASONDLast frost ~May 12First frost ~Sep 30
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)May 27September 17
50% (typical)May 12September 30
90% (likely)April 29October 13
Frost-free season (32°F, 50% chance)
139 days
Hard frost (28°F), last in spring, 50% chance after
May 2
Hard frost (28°F), first in fall, 50% chance before
October 10

The last 15 years (2006–2020 normals)

Typical last frost May 10 (2 days earlier than the 30-year normal), typical first fall frost October 3 (3 days later). Frost-free season 145 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 Cavalier: 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 9, 70% May 6, 80% May 4, 90% April 29. Observed last spring frost in recent years: 2021 May 28, 2022 May 4, 2023 April 26, 2024 April 29, 2025 April 30, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 12Apr 292021: May 282022: May 42023: April 262024: April 292025: April 302026: May 20Fall at Cavalier: chance of a frost before this dateFall, chance of a frost before the date: 10% September 17, 20% September 21, 30% September 25, 40% September 28, 50% September 30, 60% October 2, 70% October 5, 80% October 9, 90% October 13. Observed first fall frost in recent years: 2021 October 20, 2022 October 6, 2023 October 7, 2024 October 15, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 17Sep 30Oct 132021: October 202022: October 62023: October 72024: October 152025: October 8
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
2022May 4October 6
2023April 26October 7
2024April 29October 15
2025April 30October 8
2026May 20season not over yet

What these dates mean

The 139 days between the 50% light-frost dates—May 12 and September 30—define the span in which a typical growing season can be expected in Cavalier. The 50% date means there is an even chance of a frost occurring after that spring date and an even chance of a frost occurring before that fall date; they are not themselves frost dates. Light-frost risk rises sharply after the early-spring 90% date of April 29 and falls sharply before the late-fall 90% date of October 13.

For a cautious plan, tender crops should be set out after the spring cautious date of May 27, which carries only a 10% chance of a later frost, and should be finished by the fall cautious date of September 17, which carries only a 10% chance of an earlier frost. A hard frost at 28 °F—whose 50% dates are May 2 and October 10—can damage plants that survive a light frost at 32 °F, so its timing is more critical for gardeners.

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 17" 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 Cavalier, NDNumbered nearest stations: 1 — Pembina, ND — 22 mi; 2 — Argyle, MN — 54 mi; 3 — Petersburg, ND — 59 mi; 4 — Grand Forks (Airport), ND — 68 mi; 5 — near Grand Forks, ND — 71 mi.NDMN25 mi · 40 km1. Pembina, ND — 22 mi12. Argyle, MN — 54 mi23. Petersburg, ND — 59 mi34. Grand Forks (Airport), ND — 68 mi45. near Grand Forks, ND — 71 mi5
  1. Pembina, ND 22 mi (36 km)
  2. Argyle, MN 54 mi (87 km)
  3. Petersburg, ND 59 mi (95 km)
  4. Grand Forks (Airport), ND 68 mi (109 km)
  5. near Grand Forks, ND 71 mi (114 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: 48.8625, -97.7014.