U.S. Frost Dates by Weather Station

NOAA station USC00172765 · Maine

Frost Dates for Farmington, ME

NOAA weather station Farmington (USC00172765), Maine · elevation 405 ft (123 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1650% chance of a frost after it
  • Typical first fall frostSeptember 2650% chance of a frost before it
  • Frost-free season130 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Farmington, MESpring: a frost after May 3 in 9 years out of 10, after May 16 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before September 26 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 130 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 16First frost ~Sep 26Frost season at Farmington, MESpring: a frost after May 3 in 9 years out of 10, after May 16 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before September 26 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 130 days.JFMAMJJASONDLast frost ~May 16First frost ~Sep 26
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 1September 14
50% (typical)May 16September 26
90% (likely)May 3October 9
Frost-free season (32°F, 50% chance)
130 days
Hard frost (28°F), last in spring, 50% chance after
May 3
Hard frost (28°F), first in fall, 50% chance before
October 5

The last 15 years (2006–2020 normals)

Typical last frost May 17 (1 day later than the 30-year normal), typical first fall frost September 26. 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 Farmington: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 25, 30% May 22, 40% May 19, 50% May 16, 60% May 14, 70% May 10, 80% May 7, 90% May 3. Observed last spring frost in recent years: 2021 May 13, 2022 May 19, 2024 May 11, 2025 May 13, 2026 May 31.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 16May 32021: May 132022: May 192024: May 112025: May 132026: May 31Fall at Farmington: chance of a frost before this dateFall, chance of a frost before the date: 10% September 14, 20% September 18, 30% September 22, 40% September 24, 50% September 26, 60% September 29, 70% October 1, 80% October 4, 90% October 9. Observed first fall frost in recent years: 2021 October 24, 2022 September 30, 2023 October 15, 2024 October 17, 2025 September 20.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 14Sep 26Oct 92021: October 242022: September 302023: October 152024: October 172025: 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 13October 24
2022May 19September 30
2023incomplete recordOctober 15
2024May 11October 17
2025May 13September 20
2026May 31season not over yet

What these dates mean

Setting out tender crops on the early spring date, May 3, is a gamble because there is a 90% chance of a frost later than this date in Farmington.

The 50% date for light frost in spring is May 16; this marks the point where the odds of a frost later are even. In fall the 50% date is September 26, indicating equal odds of a frost earlier. A cautious planting plan therefore uses the June 1 date, which carries only a 10% chance of a frost later, while a cautious harvest deadline uses the September 14 date, which carries only a 10% chance of a frost earlier.

Hard-frost risk is tracked at 28 °F, with the 50% spring date May 3 and the 50% fall date October 5; a hard frost can injure plants that might survive a light frost, making the lower temperature threshold more significant.

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 14" 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 Farmington, MENumbered nearest stations: 1 — Madison, ME — 15 mi; 2 — near Waterville, ME — 27 mi; 3 — Rangeley, ME — 31 mi; 4 — near Augusta, ME — 31 mi; 5 — Gardiner, ME — 37 mi.NHVT25 mi · 40 km1. Madison, ME — 15 mi12. near Waterville, ME — 27 mi23. Rangeley, ME — 31 mi34. near Augusta, ME — 31 mi45. Gardiner, ME — 37 mi5
  1. Madison, ME 15 mi (24 km)
  2. near Waterville, ME 27 mi (44 km)
  3. Rangeley, ME 31 mi (49 km)
  4. near Augusta, ME 31 mi (50 km)
  5. Gardiner, ME 37 mi (60 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 44.6894, -70.1564.