U.S. Frost Dates by Weather Station

NOAA station USC00328792 · North Dakota

Frost Dates for Towner, ND

NOAA weather station Towner 2 NE (USC00328792), North Dakota · elevation 1480 ft (451 m) · hardiness zone 3b*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1750% chance of a frost after it
  • Typical first fall frostSeptember 2250% chance of a frost before it
  • Frost-free season126 daystypical year, 32°F
  • Hardiness zone3bcalculated*

The year at a glance

Frost season at Towner, NDSpring: a frost after May 5 in 9 years out of 10, after May 17 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 22 in half of the years, before October 3 in 9 years out of 10. Typical frost-free season: 126 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 17First frost ~Sep 22Frost season at Towner, NDSpring: a frost after May 5 in 9 years out of 10, after May 17 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 22 in half of the years, before October 3 in 9 years out of 10. Typical frost-free season: 126 days.JFMAMJJASONDLast frost ~May 17First frost ~Sep 22
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 1September 10
50% (typical)May 17September 22
90% (likely)May 5October 3
Frost-free season (32°F, 50% chance)
126 days
Hard frost (28°F), last in spring, 50% chance after
May 8
Hard frost (28°F), first in fall, 50% chance before
October 1

The last 15 years (2006–2020 normals)

Typical last frost May 15 (2 days earlier than the 30-year normal), typical first fall frost September 24 (2 days later). Frost-free season 130 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 Towner: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 28, 30% May 24, 40% May 20, 50% May 17, 60% May 15, 70% May 12, 80% May 9, 90% May 5. Observed last spring frost in recent years: 2021 May 29, 2024 May 25.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 17May 52021: May 292024: May 25Fall at Towner: chance of a frost before this dateFall, chance of a frost before the date: 10% September 10, 20% September 15, 30% September 18, 40% September 20, 50% September 22, 60% September 24, 70% September 27, 80% September 30, 90% October 3. Observed first fall frost in recent years: 2021 October 16.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 10Sep 22Oct 32021: October 16
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 29October 16
2022incomplete recordincomplete record
2023incomplete recordincomplete record
2024May 25incomplete record
2025incomplete recordincomplete record
2026incomplete recordseason not over yet

What these dates mean

September 10 marks the cautious fall date for finishing the harvest in Towner, when there is only a 10 % chance a light frost has arrived. For tender crops the conservative spring date is June 1, which carries a 10 % chance of a frost later, while the risky early option is May 5 with a 90 % chance. The median light-frost dates are May 17 in spring and September 22 in fall; each represents a 50 % chance of a frost occurring on either side of the date. The 50 % hard-frost dates are May 8 and October 1, dates that gardeners note without reference to before or after. A hard frost at 28 °F can injure plants more severely than a light frost at 32 °F because the colder temperature cuts off cellular activity. Using the cautious dates helps plan planting and harvesting within the 126-day window defined by the two 32 °F 50 % dates across the 28-year record.

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 10" 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 Towner, NDNumbered nearest stations: 1 — Willow City, ND — 17 mi; 2 — Rugby, ND — 18 mi; 3 — Drake, ND — 23 mi; 4 — Upham, ND — 23 mi; 5 — Bottineau, ND — 31 mi.25 mi · 40 km1. Willow City, ND — 17 mi12. Rugby, ND — 18 mi23. Drake, ND — 23 mi34. Upham, ND — 23 mi45. Bottineau, ND — 31 mi5
  1. Willow City, ND 17 mi (27 km)
  2. Rugby, ND 18 mi (29 km)
  3. Drake, ND 23 mi (36 km)
  4. Upham, ND 23 mi (37 km)
  5. Bottineau, ND 31 mi (50 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: 48.3706, -100.3908.