U.S. Frost Dates by Weather Station

NOAA station USC00173295 · Maine

Frost Dates for Gray, ME

NOAA weather station Gray (USC00173295), Maine · elevation 378 ft (115 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 10only 1 spring in 10 still has a frost later
  • Typical last frostApril 2850% chance of a frost after it
  • Typical first fall frostOctober 1950% chance of a frost before it
  • Frost-free season172 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Gray, MESpring: a frost after April 15 in 9 years out of 10, after April 28 in half of the years, after May 10 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 19 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 172 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 28First frost ~Oct 19Frost season at Gray, MESpring: a frost after April 15 in 9 years out of 10, after April 28 in half of the years, after May 10 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 19 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 172 days.JFMAMJJASONDLast frost ~Apr 28First frost ~Oct 19
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 10October 5
50% (typical)April 28October 19
90% (likely)April 15November 4
Frost-free season (32°F, 50% chance)
172 days
Hard frost (28°F), last in spring, 50% chance after
April 15
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 23 (5 days earlier than the 30-year normal), typical first fall frost October 24 (5 days later). Frost-free season 181 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 Gray: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 10, 20% May 6, 30% May 2, 40% April 30, 50% April 28, 60% April 26, 70% April 23, 80% April 20, 90% April 15. Observed last spring frost in recent years: 2021 April 23, 2022 April 21, 2023 April 10, 2024 April 27, 2025 April 12, 2026 April 22.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 10Apr 28Apr 152021: April 232022: April 212023: April 102024: April 272025: April 122026: April 22Fall at Gray: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 9, 30% October 12, 40% October 16, 50% October 19, 60% October 22, 70% October 26, 80% October 30, 90% November 4. Observed first fall frost in recent years: 2021 November 3, 2022 October 29, 2023 October 31, 2024 October 27, 2025 November 3.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 19Nov 42021: November 32022: October 292023: October 312024: October 272025: November 3
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
2021April 23November 3
2022April 21October 29
2023April 10October 31
2024April 27October 27
2025April 12November 3
2026April 22season not over yet

What these dates mean

May 10 is the cautious spring date in Gray, and it allows a gardener to set out tender crops with only a 10% chance of a later light frost.

The 50% date is April 28 in spring and October 19 in fall; these are the median points where a light frost is equally likely on either side, giving a reference for the middle of the frost-free window. The hard-frost median dates are April 15 and November 1; a hard frost can damage plants more severely than a light frost because it reaches 28 °F, a temperature that can kill tissue that survives 32 °F.

In fall, October 5 is the cautious date for finishing tender-crop harvests, carrying only a 10% chance that a light frost has already arrived; November 4 would be a gamble with a 90% chance of an earlier frost.

How to read the probabilities

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

  • Spring: "10% after May 10" 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 October 5" 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 Gray, MENumbered nearest stations: 1 — Portland, ME — 17 mi; 2 — Bridgton, ME — 27 mi; 3 — Gardiner, ME — 32 mi; 4 — Newcastle, ME — 37 mi; 5 — near Augusta, ME — 37 mi.MENH25 mi · 40 km1. Portland, ME — 17 mi12. Bridgton, ME — 27 mi23. Gardiner, ME — 32 mi34. Newcastle, ME — 37 mi45. near Augusta, ME — 37 mi5
  1. Portland, ME 17 mi (27 km)
  2. Bridgton, ME 27 mi (44 km)
  3. Gardiner, ME 32 mi (52 km)
  4. Newcastle, ME 37 mi (60 km)
  5. near Augusta, ME 37 mi (60 km)

Sources

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

Station coordinates: 43.8925, -70.2544.