U.S. Frost Dates by Weather Station

NOAA station USC00320941 · North Dakota

Frost Dates for Bottineau, ND

NOAA weather station Bottineau (USC00320941), North Dakota · elevation 1619 ft (494 m) · hardiness zone 3b*

  • Lower-risk planting dateafter May 28only 1 spring in 10 still has a frost later
  • Typical last frostMay 1550% chance of a frost after it
  • Typical first fall frostSeptember 2550% chance of a frost before it
  • Frost-free season133 daystypical year, 32°F
  • Hardiness zone3bcalculated*

The year at a glance

Frost season at Bottineau, NDSpring: a frost after May 2 in 9 years out of 10, after May 15 in half of the years, after May 28 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 25 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 133 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 15First frost ~Sep 25Frost season at Bottineau, NDSpring: a frost after May 2 in 9 years out of 10, after May 15 in half of the years, after May 28 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 25 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 133 days.JFMAMJJASONDLast frost ~May 15First frost ~Sep 25
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 28September 13
50% (typical)May 15September 25
90% (likely)May 2October 7
Frost-free season (32°F, 50% chance)
133 days
Hard frost (28°F), last in spring, 50% chance after
May 6
Hard frost (28°F), first in fall, 50% chance before
October 2

The last 15 years (2006–2020 normals)

Typical last frost May 14 (1 day earlier than the 30-year normal), typical first fall frost September 28 (3 days later). Frost-free season 136 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 Bottineau: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 28, 20% May 24, 30% May 21, 40% May 18, 50% May 15, 60% May 13, 70% May 10, 80% May 7, 90% May 2. Observed last spring frost in recent years: 2021 May 10, 2022 May 22, 2023 May 2, 2024 April 30, 2025 April 30.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 28May 15May 22021: May 102022: May 222023: May 22024: April 302025: April 30Fall at Bottineau: chance of a frost before this dateFall, chance of a frost before the date: 10% September 13, 20% September 18, 30% September 21, 40% September 23, 50% September 25, 60% September 28, 70% September 30, 80% October 3, 90% October 7. Observed first fall frost in recent years: 2021 October 16, 2022 October 7, 2023 October 7, 2024 October 1, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 13Sep 25Oct 72021: October 162022: October 72023: October 72024: October 12025: 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 16
2022May 22October 7
2023May 2October 7
2024April 30October 1
2025April 30October 6
2026incomplete recordseason not over yet

What these dates mean

May 28 is the cautious spring date for light frost in Bottineau, and it gives a gardener the confidence to set out tender crops with only a 10 % chance of a later frost. The 50 % date is May 15, which means a 50 % chance of a light frost later than this date. By contrast, May 2 carries a 90 % chance of a later frost and is a gamble for early planting.

September 13 is the cautious fall date for light frost, allowing a gardener to finish harvesting tender crops with only a 10 % chance that frost has already arrived. The 50 % date is September 25, indicating a 50 % chance of a light frost earlier than this date. October 7 carries a 90 % chance of an earlier frost, making a late-season planting a gamble. The hard-frost 50 % dates are May 6 and October 2; a hard frost can damage plants more severely than a light 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 13" 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 Bottineau, NDNumbered nearest stations: 1 — Willow City, ND — 17 mi; 2 — Upham, ND — 19 mi; 3 — Towner, ND — 31 mi; 4 — Rugby, ND — 39 mi; 5 — Drake, ND — 54 mi.25 mi · 40 km1. Willow City, ND — 17 mi12. Upham, ND — 19 mi23. Towner, ND — 31 mi34. Rugby, ND — 39 mi45. Drake, ND — 54 mi5
  1. Willow City, ND 17 mi (27 km)
  2. Upham, ND 19 mi (31 km)
  3. Towner, ND 31 mi (50 km)
  4. Rugby, ND 39 mi (62 km)
  5. Drake, ND 54 mi (87 km)

Sources

* Hardiness zone 3b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 48.8217, -100.4528.