U.S. Frost Dates by Weather Station

NOAA station USC00275995 · New Hampshire

Frost Dates for North Conway, NH

NOAA weather station North Conway (USC00275995), New Hampshire · elevation 522 ft (159 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 19only 1 spring in 10 still has a frost later
  • Typical last frostMay 750% chance of a frost after it
  • Typical first fall frostOctober 550% chance of a frost before it
  • Frost-free season150 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at North Conway, NHSpring: a frost after April 27 in 9 years out of 10, after May 7 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 5 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 150 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 7First frost ~Oct 5Frost season at North Conway, NHSpring: a frost after April 27 in 9 years out of 10, after May 7 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 5 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 150 days.JFMAMJJASONDLast frost ~May 7First frost ~Oct 5
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 19September 23
50% (typical)May 7October 5
90% (likely)April 27October 20
Frost-free season (32°F, 50% chance)
150 days
Hard frost (28°F), last in spring, 50% chance after
April 26
Hard frost (28°F), first in fall, 50% chance before
October 17

The last 15 years (2006–2020 normals)

Typical last frost May 4 (3 days earlier than the 30-year normal), typical first fall frost October 12 (7 days later). Frost-free season 160 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 North Conway: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 19, 20% May 16, 30% May 13, 40% May 10, 50% May 7, 60% May 5, 70% May 2, 80% April 30, 90% April 27. Observed last spring frost in recent years: 2021 April 24, 2022 May 1, 2023 May 19, 2024 April 27, 2025 April 22, 2026 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 19May 7Apr 272021: April 242022: May 12023: May 192024: April 272025: April 222026: May 12Fall at North Conway: chance of a frost before this dateFall, chance of a frost before the date: 10% September 23, 20% September 28, 30% October 1, 40% October 2, 50% October 5, 60% October 7, 70% October 10, 80% October 15, 90% October 20. Observed first fall frost in recent years: 2021 October 28, 2022 October 9, 2023 October 24, 2024 October 17, 2025 October 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 23Oct 5Oct 202021: October 282022: October 92023: October 242024: October 172025: 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 24October 28
2022May 1October 9
2023May 19October 24
2024April 27October 17
2025April 22October 10
2026May 12season not over yet

What these dates mean

The 150 days between the 32°F 50% dates—May 7 and October 5—define the window in North Conway when light frosts are equally likely to have occurred or not, so a gardener can expect an even chance of a frost later than May 7 in spring and earlier than October 5 in fall. Because the chance of a light frost is 50 % on those dates, they serve as reference points for planning, while the risk rises sharply outside them.

For a cautious plan, tender crops are best set out after the May 19 date, which carries only a 10 % chance of a later light frost, and harvested before the September 23 date, which holds only a 10 % chance of an earlier light frost. Hard frost at 28°F—median dates April 26 in spring and October 17 in fall—poses a greater threat to plant tissue than the 32°F light frost.

How to read the probabilities

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

  • Spring: "10% after May 19" 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 23" 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 North Conway, NHNumbered nearest stations: 1 — Pinkham Notch, NH — 15 mi; 2 — Bridgton, ME — 19 mi; 3 — Berlin, NH — 28 mi; 4 — York Pond, NH — 33 mi; 5 — Lancaster, NH — 38 mi.MENHVT25 mi · 40 km1. Pinkham Notch, NH — 15 mi12. Bridgton, ME — 19 mi23. Berlin, NH — 28 mi34. York Pond, NH — 33 mi45. Lancaster, NH — 38 mi5
  1. Pinkham Notch, NH 15 mi (25 km)
  2. Bridgton, ME 19 mi (31 km)
  3. Berlin, NH 28 mi (44 km)
  4. York Pond, NH 33 mi (53 km)
  5. Lancaster, NH 38 mi (60 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: 44.0561, -71.1297.