U.S. Frost Dates by Weather Station

NOAA station USC00179593 · Maine

Frost Dates for West Rockport, ME

NOAA weather station West Rockport 1 NNW (USC00179593), Maine · elevation 361 ft (110 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 9only 1 spring in 10 still has a frost later
  • Typical last frostApril 2750% chance of a frost after it
  • Typical first fall frostOctober 1950% chance of a frost before it
  • Frost-free season175 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at West Rockport, MESpring: a frost after April 17 in 9 years out of 10, after April 27 in half of the years, after May 9 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 3 in 9 years out of 10. Typical frost-free season: 175 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 27First frost ~Oct 19Frost season at West Rockport, MESpring: a frost after April 17 in 9 years out of 10, after April 27 in half of the years, after May 9 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 3 in 9 years out of 10. Typical frost-free season: 175 days.JFMAMJJASONDLast frost ~Apr 27First 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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 9October 5
50% (typical)April 27October 19
90% (likely)April 17November 3
Frost-free season (32°F, 50% chance)
175 days
Hard frost (28°F), last in spring, 50% chance after
April 15
Hard frost (28°F), first in fall, 50% chance before
October 31

The last 15 years (2006–2020 normals)

Typical last frost April 23 (4 days earlier than the 30-year normal), typical first fall frost October 26 (7 days later). Frost-free season 182 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 West Rockport: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 9, 20% May 4, 30% May 1, 40% April 29, 50% April 27, 60% April 25, 70% April 23, 80% April 21, 90% April 17. Observed last spring frost in recent years: 2021 April 23, 2022 April 21, 2023 May 18, 2024 April 26, 2025 April 18, 2026 April 25.Spring: last frostChance of a frost after this date10%50%90%May 1May 9Apr 27Apr 172021: April 232022: April 212023: May 182024: April 262025: April 182026: April 25Fall at West Rockport: 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 15, 50% October 19, 60% October 22, 70% October 25, 80% October 29, 90% November 3. Observed first fall frost in recent years: 2021 October 24, 2022 November 9, 2023 October 31, 2024 October 28, 2025 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 19Nov 32021: October 242022: November 92023: October 312024: October 282025: November 2
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 23October 24
2022April 21November 9
2023May 18October 31
2024April 26October 28
2025April 18November 2
2026April 25season not over yet

What these dates mean

May 9 is the cautious spring date in West Rockport; on that day there is only a 10 % chance of a light frost later, so a gardener can plan to set out tender crops with relatively low risk. The counterpart in fall is October 5, the cautious date when there is only a 10 % chance that a light frost has already arrived, allowing the gardener to finish harvesting tender crops.

The 50 % light-frost date is April 27, which means a 50 % chance of a frost later than this date, and the 50 % fall date is October 19, with a 50 % chance of a frost earlier than this date. The median hard-frost dates are April 15 and October 31; hard frost at 28 °F can damage plants more severely than a light frost at 32 °F, so those dates are especially important for protecting vulnerable crops.

How to read the probabilities

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

  • Spring: "10% after May 9" 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 West Rockport, MENumbered nearest stations: 1 — Tenants Harbor, ME — 14 mi; 2 — Belfast, ME — 16 mi; 3 — Newcastle, ME — 22 mi; 4 — Gardiner, ME — 32 mi; 5 — near Augusta, ME — 33 mi.ME25 mi · 40 km1. Tenants Harbor, ME — 14 mi12. Belfast, ME — 16 mi23. Newcastle, ME — 22 mi34. Gardiner, ME — 32 mi45. near Augusta, ME — 33 mi5
  1. Tenants Harbor, ME 14 mi (23 km)
  2. Belfast, ME 16 mi (26 km)
  3. Newcastle, ME 22 mi (35 km)
  4. Gardiner, ME 32 mi (51 km)
  5. near Augusta, ME 33 mi (54 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: 44.1922, -69.1467.