U.S. Frost Dates by Weather Station

NOAA station USC00177238 · Maine

Frost Dates for Robbinston, ME

NOAA weather station Robbinston (USC00177238), Maine · elevation 115 ft (35 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 18only 1 spring in 10 still has a frost later
  • Typical last frostMay 550% chance of a frost after it
  • Typical first fall frostOctober 1350% chance of a frost before it
  • Frost-free season160 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Robbinston, MESpring: a frost after April 24 in 9 years out of 10, after May 5 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 13 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 160 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 5First frost ~Oct 13Frost season at Robbinston, MESpring: a frost after April 24 in 9 years out of 10, after May 5 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 13 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 160 days.JFMAMJJASONDLast frost ~May 5First frost ~Oct 13
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 18October 1
50% (typical)May 5October 13
90% (likely)April 24October 30
Frost-free season (32°F, 50% chance)
160 days
Hard frost (28°F), last in spring, 50% chance after
April 21
Hard frost (28°F), first in fall, 50% chance before
October 28

The last 15 years (2006–2020 normals)

Typical last frost May 2 (3 days earlier than the 30-year normal), typical first fall frost October 16 (3 days later). Frost-free season 165 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 Robbinston: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 18, 20% May 13, 30% May 10, 40% May 7, 50% May 5, 60% May 2, 70% April 30, 80% April 28, 90% April 24. Observed last spring frost in recent years: 2021 April 23, 2022 May 9, 2023 May 10, 2024 May 10, 2025 May 1, 2026 May 3.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 18May 5Apr 242021: April 232022: May 92023: May 102024: May 102025: May 12026: May 3Fall at Robbinston: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 4, 30% October 7, 40% October 10, 50% October 13, 60% October 16, 70% October 20, 80% October 24, 90% October 30. Observed first fall frost in recent years: 2021 November 5, 2022 October 3, 2023 October 24, 2024 October 16, 2025 October 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 13Oct 302021: November 52022: October 32023: October 242024: October 162025: October 10
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 5
2022May 9October 3
2023May 10October 24
2024May 10October 16
2025May 1October 10
2026May 3season not over yet

What these dates mean

Setting out tender crops on April 24 in Robbinston carries a 90 % chance of a light frost later, making that early planting a gamble. The cautious approach waits until May 18, when only a 10 % chance of a light frost remains, and in the fall the safest finish date for tender crops is October 1, with only a 10 % chance that a frost has already arrived.

The 50 % dates represent the point at which the odds of a light frost are even. In spring the median date is May 5, and in fall it is October 13; at those dates a gardener faces a fifty-fifty chance of a frost occurring later (spring) or earlier (fall). The median hard-frost dates are April 21 in spring and October 28 in fall.

A hard frost at 28 °F can damage plants that would survive a light frost at 32 °F, so it is a more critical threshold.

How to read the probabilities

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

  • Spring: "10% after May 18" 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 1" 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 Robbinston, MENumbered nearest stations: 1 — Woodland, ME — 14 mi; 2 — Houlton, ME — 79 mi; 3 — Bangor, ME — 85 mi; 4 — Bridgewater, ME — 99 mi; 5 — Dover-Foxcroft, ME — 101 mi.ME50 mi · 80 km1. Woodland, ME — 14 mi12. Houlton, ME — 79 mi23. Bangor, ME — 85 mi34. Bridgewater, ME — 99 mi45. Dover-Foxcroft, ME — 101 mi5
  1. Woodland, ME 14 mi (23 km)
  2. Houlton, ME 79 mi (127 km)
  3. Bangor, ME 85 mi (137 km)
  4. Bridgewater, ME 99 mi (160 km)
  5. Dover-Foxcroft, ME 101 mi (162 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: 45.0853, -67.1206.