U.S. Frost Dates by Weather Station

NOAA station USC00174086 · Maine

Frost Dates for Jackman, ME

NOAA weather station Jackman (USC00174086), Maine · elevation 1214 ft (370 m) · hardiness zone 4b*

  • Lower-risk planting dateafter June 7only 1 spring in 10 still has a frost later
  • Typical last frostMay 2650% chance of a frost after it
  • Typical first fall frostSeptember 2350% chance of a frost before it
  • Frost-free season119 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Jackman, MESpring: a frost after May 10 in 9 years out of 10, after May 26 in half of the years, after June 7 in 1 year out of 10. Fall: the first frost comes before September 8 in 1 year out of 10, before September 23 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 119 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 26First frost ~Sep 23Frost season at Jackman, MESpring: a frost after May 10 in 9 years out of 10, after May 26 in half of the years, after June 7 in 1 year out of 10. Fall: the first frost comes before September 8 in 1 year out of 10, before September 23 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 119 days.JFMAMJJASONDLast frost ~May 26First frost ~Sep 23
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 7September 8
50% (typical)May 26September 23
90% (likely)May 10October 5
Frost-free season (32°F, 50% chance)
119 days
Hard frost (28°F), last in spring, 50% chance after
May 11
Hard frost (28°F), first in fall, 50% chance before
October 3

The last 15 years (2006–2020 normals)

Typical last frost May 23 (3 days earlier than the 30-year normal), typical first fall frost September 23. Frost-free season 122 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 Jackman: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 7, 20% June 4, 30% June 1, 40% May 29, 50% May 26, 60% May 24, 70% May 20, 80% May 16, 90% May 10. Observed last spring frost in recent years: 2021 May 30, 2022 May 24, 2023 May 23, 2024 May 11, 2025 June 4, 2026 June 1.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 7May 26May 102021: May 302022: May 242023: May 232024: May 112025: June 42026: June 1Fall at Jackman: chance of a frost before this dateFall, chance of a frost before the date: 10% September 8, 20% September 12, 30% September 17, 40% September 20, 50% September 23, 60% September 25, 70% September 28, 80% October 1, 90% October 5. Observed first fall frost in recent years: 2021 September 29, 2022 September 17, 2023 October 24, 2024 October 9, 2025 September 20.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 8Sep 23Oct 52021: September 292022: September 172023: October 242024: 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 30September 29
2022May 24September 17
2023May 23October 24
2024May 11October 9
2025June 4September 20
2026June 1season not over yet

What these dates mean

September 8 marks the cautious fall date for finishing the harvest in Jackman, with only a 10 % chance that a light frost has arrived earlier.

For light frost, the 50 % dates are May 26 in spring and September 23 in fall; at each of those dates the chance of a frost is exactly fifty-fifty, indicating an even balance of risk. A cautious planting schedule therefore relies on the June 7 date, which carries a 10 % chance of a frost later, for setting out tender crops in spring, and on the September 8 date, which carries a 10 % chance of a frost earlier, for concluding tender-crop harvests in fall.

Hard frost at 28 °F, reflected by the median dates May 11 and October 3, matters more than a light frost because it can damage plants that would survive a 32 °F event.

How to read the probabilities

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

  • Spring: "10% after June 7" 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 8" 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 Jackman, MENumbered nearest stations: 1 — Brassua Dam, ME — 21 mi; 2 — Eustis, ME — 31 mi; 3 — Rangeley, ME — 49 mi; 4 — Dover-Foxcroft, ME — 60 mi; 5 — Madison, ME — 60 mi.MENH25 mi · 40 km1. Brassua Dam, ME — 21 mi12. Eustis, ME — 31 mi23. Rangeley, ME — 49 mi34. Dover-Foxcroft, ME — 60 mi45. Madison, ME — 60 mi5
  1. Brassua Dam, ME 21 mi (34 km)
  2. Eustis, ME 31 mi (50 km)
  3. Rangeley, ME 49 mi (80 km)
  4. Dover-Foxcroft, ME 60 mi (96 km)
  5. Madison, ME 60 mi (96 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: 45.6261, -70.2461.