U.S. Frost Dates by Weather Station

NOAA station USC00272999 · New Hampshire

Frost Dates for First Connecticut Lake, NH

NOAA weather station First Connecticut Lake (USC00272999), New Hampshire · elevation 1650 ft (503 m) · hardiness zone 4a*

  • Lower-risk planting dateafter June 8only 1 spring in 10 still has a frost later
  • Typical last frostMay 2550% chance of a frost after it
  • Typical first fall frostSeptember 2450% chance of a frost before it
  • Frost-free season121 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at First Connecticut Lake, NHSpring: a frost after May 9 in 9 years out of 10, after May 25 in half of the years, after June 8 in 1 year out of 10. Fall: the first frost comes before September 9 in 1 year out of 10, before September 24 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 121 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 25First frost ~Sep 24Frost season at First Connecticut Lake, NHSpring: a frost after May 9 in 9 years out of 10, after May 25 in half of the years, after June 8 in 1 year out of 10. Fall: the first frost comes before September 9 in 1 year out of 10, before September 24 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 121 days.JFMAMJJASONDLast frost ~May 25First frost ~Sep 24
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)June 8September 9
50% (typical)May 25September 24
90% (likely)May 9October 7
Frost-free season (32°F, 50% chance)
121 days
Hard frost (28°F), last in spring, 50% chance after
May 9
Hard frost (28°F), first in fall, 50% chance before
October 5

The last 15 years (2006–2020 normals)

Typical last frost May 24 (1 day earlier than the 30-year normal), typical first fall frost September 25 (1 day later). Frost-free season 124 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 First Connecticut Lake: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 8, 20% June 4, 30% May 31, 40% May 28, 50% May 25, 60% May 21, 70% May 18, 80% May 14, 90% May 9. Observed last spring frost in recent years: 2021 May 30, 2022 May 24, 2023 May 26, 2024 May 10, 2025 May 26, 2026 May 31.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 8May 25May 92021: May 302022: May 242023: May 262024: May 102025: May 262026: May 31Fall at First Connecticut Lake: chance of a frost before this dateFall, chance of a frost before the date: 10% September 9, 20% September 14, 30% September 18, 40% September 21, 50% September 24, 60% September 27, 70% September 30, 80% October 2, 90% October 7. Observed first fall frost in recent years: 2021 October 24, 2022 September 30, 2023 October 24, 2024 October 13, 2025 September 20.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 9Sep 24Oct 72021: October 242022: September 302023: October 242024: October 132025: September 20
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
2021May 30October 24
2022May 24September 30
2023May 26October 24
2024May 10October 13
2025May 26September 20
2026May 31season not over yet

What these dates mean

The 121 days between the 50% dates in First Connecticut Lake define the core growing window for tender crops. The 50% date of May 25 marks the point with a 50% chance of a light frost later, while the 50% date of September 24 marks the point with a 50% chance of a light frost earlier. Those dates are not frost dates but indicate when the odds balance.

For a cautious spring schedule, the 10 % chance date is June 8, the date a gardener should aim to set out tender crops. In the fall, the cautious date is September 9, the date with only a 10 % chance that a light frost has arrived, suitable for finishing harvest. A hard frost at 28 °F can cause far more severe injury than a light frost at 32 °F, making the hard-frost 50% dates of May 9 and October 5 important reference points.

How to read the probabilities

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

  • Spring: "10% after June 8" 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 9" 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 First Connecticut Lake, NHNumbered nearest stations: 1 — Colebrook, NH — 20 mi; 2 — Rangeley, ME — 33 mi; 3 — Island Pond, VT — 35 mi; 4 — York Pond, NH — 40 mi; 5 — Eustis, ME — 41 mi.MEVTNH25 mi · 40 km1. Colebrook, NH — 20 mi12. Rangeley, ME — 33 mi23. Island Pond, VT — 35 mi34. York Pond, NH — 40 mi45. Eustis, ME — 41 mi5
  1. Colebrook, NH 20 mi (32 km)
  2. Rangeley, ME 33 mi (53 km)
  3. Island Pond, VT 35 mi (56 km)
  4. York Pond, NH 40 mi (65 km)
  5. Eustis, ME 41 mi (66 km)

Sources

* Hardiness zone 4a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 45.09, -71.2906.