U.S. Frost Dates by Weather Station

NOAA station USC00172878 · Maine

Frost Dates for Fort Kent, ME

NOAA weather station Fort Kent (USC00172878), Maine · elevation 610 ft (186 m) · hardiness zone 4a*

  • Lower-risk planting dateafter June 6only 1 spring in 10 still has a frost later
  • Typical last frostMay 2350% chance of a frost after it
  • Typical first fall frostSeptember 2450% chance of a frost before it
  • Frost-free season121 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Fort Kent, MESpring: a frost after May 8 in 9 years out of 10, after May 23 in half of the years, after June 6 in 1 year out of 10. Fall: the first frost comes before September 11 in 1 year out of 10, before September 24 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 121 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 23First frost ~Sep 24Frost season at Fort Kent, MESpring: a frost after May 8 in 9 years out of 10, after May 23 in half of the years, after June 6 in 1 year out of 10. Fall: the first frost comes before September 11 in 1 year out of 10, before September 24 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 121 days.JFMAMJJASONDLast frost ~May 23First frost ~Sep 24
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)June 6September 11
50% (typical)May 23September 24
90% (likely)May 8October 5
Frost-free season (32°F, 50% chance)
121 days
Hard frost (28°F), last in spring, 50% chance after
May 9
Hard frost (28°F), first in fall, 50% chance before
October 3

The last 15 years (2006–2020 normals)

Typical last frost May 21 (2 days earlier than the 30-year normal), typical first fall frost September 25 (1 day later). Frost-free season 126 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 Fort Kent: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 6, 20% June 2, 30% May 29, 40% May 26, 50% May 23, 60% May 20, 70% May 16, 80% May 12, 90% May 8. Observed last spring frost in recent years: 2021 May 30, 2022 May 24, 2023 May 23, 2024 May 11, 2025 May 22, 2026 May 30.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 6May 23May 82021: May 302022: May 242023: May 232024: May 112025: May 222026: May 30Fall at Fort Kent: chance of a frost before this dateFall, chance of a frost before the date: 10% September 11, 20% September 15, 30% September 19, 40% September 21, 50% September 24, 60% September 26, 70% September 29, 80% October 1, 90% October 5. Observed first fall frost in recent years: 2021 October 5, 2022 September 19, 2023 October 18, 2024 October 9, 2025 September 20.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 11Sep 24Oct 52021: October 52022: September 192023: October 182024: October 92025: September 20
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 30October 5
2022May 24September 19
2023May 23October 18
2024May 11October 9
2025May 22September 20
2026May 30season not over yet

What these dates mean

September 11 marks the cautious fall date for finishing the harvest of tender crops in Fort Kent; there is only a 10 % chance that a light frost has arrived earlier.

For light frost (32 °F) the 50% dates are May 23 and September 24; each represents an even-odds point in the seasonal frost probability. In spring the cautious date for setting out tender crops is June 6, when the chance of a frost later than that date is just 10 %. In fall the cautious date to complete harvesting tender crops is September 11, with only a 10 % chance that a frost has already occurred.

Hard frost at 28 °F, reflected by the median dates May 9 and October 3, can damage plants more severely than a light frost, so its occurrence is a greater concern for growers.

How to read the probabilities

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

  • Spring: "10% after June 6" 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 Fort Kent, MENumbered nearest stations: 1 — Van Buren, ME — 32 mi; 2 — Caribou, ME — 38 mi; 3 — Presque Isle, ME — 49 mi; 4 — Bridgewater, ME — 67 mi; 5 — Houlton, ME — 86 mi.ME25 mi · 40 km1. Van Buren, ME — 32 mi12. Caribou, ME — 38 mi23. Presque Isle, ME — 49 mi34. Bridgewater, ME — 67 mi45. Houlton, ME — 86 mi5
  1. Van Buren, ME 32 mi (51 km)
  2. Caribou, ME 38 mi (61 km)
  3. Presque Isle, ME 49 mi (80 km)
  4. Bridgewater, ME 67 mi (107 km)
  5. Houlton, ME 86 mi (139 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: 47.2386, -68.6119.