U.S. Frost Dates by Weather Station

NOAA station USC00179151 · Maine

Frost Dates near Waterville, ME

NOAA weather station Waterville Trtmt Plant (USC00179151), Maine · elevation 73 ft (22 m) · hardiness zone 5b*

Waterville is the nearest town to the station (2.1 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 14only 1 spring in 10 still has a frost later
  • Typical last frostMay 250% chance of a frost after it
  • Typical first fall frostOctober 1050% chance of a frost before it
  • Frost-free season159 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season near Waterville, MESpring: a frost after April 23 in 9 years out of 10, after May 2 in half of the years, after May 14 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 10 in half of the years, before October 27 in 9 years out of 10. Typical frost-free season: 159 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 2First frost ~Oct 10Frost season near Waterville, MESpring: a frost after April 23 in 9 years out of 10, after May 2 in half of the years, after May 14 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 10 in half of the years, before October 27 in 9 years out of 10. Typical frost-free season: 159 days.JFMAMJJASONDLast frost ~May 2First frost ~Oct 10
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.Today

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 14September 30
50% (typical)May 2October 10
90% (likely)April 23October 27
Frost-free season (32°F, 50% chance)
159 days
Hard frost (28°F), last in spring, 50% chance after
April 22
Hard frost (28°F), first in fall, 50% chance before
October 24

The last 15 years (2006–2020 normals)

Typical last frost May 1 (1 day earlier than the 30-year normal), typical first fall frost October 13 (3 days later). Frost-free season 163 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 near Waterville: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 14, 20% May 10, 30% May 7, 40% May 5, 50% May 2, 60% May 1, 70% April 29, 80% April 27, 90% April 23. Observed last spring frost in recent years: 2021 April 23, 2022 May 8, 2023 May 19, 2024 April 27, 2025 April 24, 2026 May 9.Spring: last frostChance of a frost after this date10%50%90%May 1May 14May 2Apr 232021: April 232022: May 82023: May 192024: April 272025: April 242026: May 9Fall near Waterville: chance of a frost before this dateFall, chance of a frost before the date: 10% September 30, 20% October 2, 30% October 5, 40% October 7, 50% October 10, 60% October 13, 70% October 17, 80% October 20, 90% October 27. Observed first fall frost in recent years: 2021 October 24, 2022 October 3, 2023 October 31, 2024 October 17, 2025 September 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 30Oct 10Oct 272021: October 242022: October 32023: October 312024: October 172025: September 19
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
2022May 8October 3
2023May 19October 31
2024April 27October 17
2025April 24September 19
2026May 9season not over yet

What these dates mean

The 159 days between the 50% light-frost dates of May 2 and October 10 define the period in which tender crops can be grown in the Waterville area. The median dates themselves are not frost dates; they simply mark the point at which a light frost is equally likely to occur earlier or later.

Gardeners planning a cautious schedule would wait until May 14 in spring, which carries a 10 % chance of a light frost later, before setting out tender crops. In fall the comparable cautious date is September 30, when there is a 10 % chance that a light frost has already arrived, signaling the latest date to finish harvesting tender crops.

A hard frost of 28 °F, represented by the median dates April 22 and October 24, can damage plants more severely than a light frost of 32 °F, so its timing is especially significant.

How to read the probabilities

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

  • Spring: "10% after May 14" 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 30" 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 Waterville, MENumbered nearest stations: 1 — near Augusta, ME — 16 mi; 2 — Madison, ME — 22 mi; 3 — Gardiner, ME — 22 mi; 4 — Farmington, ME — 27 mi; 5 — Corinna, ME — 34 mi.NH25 mi · 40 km1. near Augusta, ME — 16 mi12. Madison, ME — 22 mi23. Gardiner, ME — 22 mi34. Farmington, ME — 27 mi45. Corinna, ME — 34 mi5
  1. near Augusta, ME 16 mi (26 km)
  2. Madison, ME 22 mi (35 km)
  3. Gardiner, ME 22 mi (36 km)
  4. Farmington, ME 27 mi (44 km)
  5. Corinna, ME 34 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: 44.5272, -69.6544.