U.S. Frost Dates by Weather Station

NOAA station USC00171975 · Maine

Frost Dates for Dover-Foxcroft, ME

NOAA weather station Dover-Foxcroft WWTP (USC00171975), Maine · elevation 370 ft (113 m) · hardiness zone 4b*

  • 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 2850% chance of a frost before it
  • Frost-free season134 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Dover-Foxcroft, MESpring: a frost after April 30 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 15 in 1 year out of 10, before September 28 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 134 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 15First frost ~Sep 28Frost season at Dover-Foxcroft, MESpring: a frost after April 30 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 15 in 1 year out of 10, before September 28 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 134 days.JFMAMJJASONDLast frost ~May 15First frost ~Sep 28
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)May 28September 15
50% (typical)May 15September 28
90% (likely)April 30October 9
Frost-free season (32°F, 50% chance)
134 days
Hard frost (28°F), last in spring, 50% chance after
May 2
Hard frost (28°F), first in fall, 50% chance before
October 9

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 30 (2 days later). Frost-free season 139 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 Dover-Foxcroft: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 28, 20% May 24, 30% May 20, 40% May 18, 50% May 15, 60% May 12, 70% May 8, 80% May 5, 90% April 30. Observed last spring frost in recent years: 2021 May 8, 2022 May 19, 2023 May 19, 2024 May 10, 2025 May 12, 2026 May 31.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 28May 15Apr 302021: May 82022: May 192023: May 192024: May 102025: May 122026: May 31Fall at Dover-Foxcroft: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 20, 30% September 23, 40% September 25, 50% September 28, 60% September 30, 70% October 2, 80% October 5, 90% October 9. Observed first fall frost in recent years: 2021 October 25, 2022 September 30, 2023 October 24, 2024 October 17, 2025 September 20.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Nov 1Sep 15Sep 28Oct 92021: October 252022: September 302023: October 242024: 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 8October 25
2022May 19September 30
2023May 19October 24
2024May 10October 17
2025May 12September 20
2026May 31season not over yet

What these dates mean

May 28 is the cautious spring date for Dover-Foxcroft, carrying only a 10 % chance that a light frost will occur later; this gives a gardener enough confidence to set out tender crops at that time. By contrast, planting on April 30 would be a gamble with a 90 % chance of a frost after the date.

The 50% light-frost dates are May 15 in spring and September 28 in fall; each marks the point where a frost is equally likely to occur before or after, helping a gardener gauge the middle of the frost-risk window. The 50% hard-frost dates are May 2 and October 9, indicating the median timing for temperatures that drop to 28 °F.

The cautious fall date is September 15, when there is only a 10 % chance that a light frost has already arrived, allowing a gardener to finish harvesting tender crops. A hard frost matters more than a light frost because the 28 °F threshold can damage plant tissue that survives the milder 32 °F conditions.

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 15" 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 Dover-Foxcroft, MENumbered nearest stations: 1 — Corinna, ME — 19 mi; 2 — Bangor, ME — 32 mi; 3 — Madison, ME — 44 mi; 4 — Brassua Dam, ME — 45 mi; 5 — near Waterville, ME — 51 mi.NH25 mi · 40 km1. Corinna, ME — 19 mi12. Bangor, ME — 32 mi23. Madison, ME — 44 mi34. Brassua Dam, ME — 45 mi45. near Waterville, ME — 51 mi5
  1. Corinna, ME 19 mi (30 km)
  2. Bangor, ME 32 mi (52 km)
  3. Madison, ME 44 mi (70 km)
  4. Brassua Dam, ME 45 mi (72 km)
  5. near Waterville, ME 51 mi (82 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 45.1872, -69.1842.