U.S. Frost Dates by Weather Station

NOAA station USC00174193 · Maine

Frost Dates for Kennebunkport, ME

NOAA weather station Kennebunkport (USC00174193), Maine · elevation 20 ft (6 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 950% chance of a frost after it
  • Typical first fall frostOctober 350% chance of a frost before it
  • Frost-free season146 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Kennebunkport, MESpring: a frost after April 28 in 9 years out of 10, after May 9 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 3 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 9First frost ~Oct 3Frost season at Kennebunkport, MESpring: a frost after April 28 in 9 years out of 10, after May 9 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 3 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 146 days.JFMAMJJASONDLast frost ~May 9First frost ~Oct 3
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 22September 20
50% (typical)May 9October 3
90% (likely)April 28October 19
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 5 (4 days earlier than the 30-year normal), typical first fall frost October 9 (6 days later). Frost-free season 155 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 Kennebunkport: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 18, 30% May 14, 40% May 11, 50% May 9, 60% May 6, 70% May 4, 80% May 1, 90% April 28. Observed last spring frost in recent years: 2021 April 27, 2022 May 11, 2023 May 18, 2024 May 11, 2025 May 1, 2026 May 9.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 9Apr 282021: April 272022: May 112023: May 182024: May 112025: May 12026: May 9Fall at Kennebunkport: chance of a frost before this dateFall, chance of a frost before the date: 10% September 20, 20% September 26, 30% September 29, 40% October 1, 50% October 3, 60% October 6, 70% October 9, 80% October 13, 90% October 19. Observed first fall frost in recent years: 2021 October 24, 2022 October 9, 2023 October 24, 2024 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 20Oct 3Oct 192021: October 242022: October 92023: October 242024: October 17
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 27October 24
2022May 11October 9
2023May 18October 24
2024May 11October 17
2025May 1incomplete record
2026May 9season not over yet

What these dates mean

September 20 is the cautious fall date for finishing the harvest in Kennebunkport, when there is only a 10 % chance that a light frost has arrived earlier. Gardeners who wait until the 90 % risk date of October 19 risk a frost for tender crops, while those who aim for the 50 % date of October 3 know the odds are even.

In spring the cautious date for setting out tender crops is May 22, which carries a 10 % chance of a later light frost; the gamble date is April 28 with a 90 % chance. The median light-frost dates are May 9 and October 3, points where the chance of frost is 50 %. The hard-frost 50 % dates are April 29 in spring and October 15 in fall, and a hard frost at 28 °F can injure plants more severely than a light frost at 32 °F.

How to read the probabilities

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

  • Spring: "10% after May 22" 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 20" 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 Kennebunkport, MENumbered nearest stations: 1 — Portland, ME — 22 mi; 2 — Durham, NH — 28 mi; 3 — Greenland, NH — 30 mi; 4 — Gray, ME — 38 mi; 5 — Epping, NH — 38 mi.NHVT25 mi · 40 km1. Portland, ME — 22 mi12. Durham, NH — 28 mi23. Greenland, NH — 30 mi34. Gray, ME — 38 mi45. Epping, NH — 38 mi5
  1. Portland, ME 22 mi (35 km)
  2. Durham, NH 28 mi (46 km)
  3. Greenland, NH 30 mi (48 km)
  4. Gray, ME 38 mi (62 km)
  5. Epping, NH 38 mi (62 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 43.3606, -70.4697.