U.S. Frost Dates by Weather Station

NOAA station USC00270690 · New Hampshire

Frost Dates for Berlin, NH

NOAA weather station Berlin (USC00270690), New Hampshire · elevation 920 ft (280 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 30only 1 spring in 10 still has a frost later
  • Typical last frostMay 1450% chance of a frost after it
  • Typical first fall frostSeptember 3050% chance of a frost before it
  • Frost-free season135 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Berlin, NHSpring: a frost after April 30 in 9 years out of 10, after May 14 in half of the years, after May 30 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 30 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 135 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 14First frost ~Sep 30Frost season at Berlin, NHSpring: a frost after April 30 in 9 years out of 10, after May 14 in half of the years, after May 30 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 30 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 135 days.JFMAMJJASONDLast frost ~May 14First frost ~Sep 30
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 30September 15
50% (typical)May 14September 30
90% (likely)April 30October 11
Frost-free season (32°F, 50% chance)
135 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 10

The last 15 years (2006–2020 normals)

Typical last frost May 12 (2 days earlier than the 30-year normal), typical first fall frost October 1 (1 day later). Frost-free season 140 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 Berlin: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 30, 20% May 25, 30% May 20, 40% May 17, 50% May 14, 60% May 11, 70% May 8, 80% May 5, 90% April 30. Observed last spring frost in recent years: 2021 May 7, 2022 May 9, 2023 May 26, 2024 April 28, 2025 May 1, 2026 May 23.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 30May 14Apr 302021: May 72022: May 92023: May 262024: April 282025: May 12026: May 23Fall at Berlin: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 20, 30% September 23, 40% September 26, 50% September 30, 60% October 1, 70% October 4, 80% October 7, 90% October 11. Observed first fall frost in recent years: 2021 October 25, 2022 September 30, 2023 October 24, 2024 October 17, 2025 September 20.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Nov 1Sep 15Sep 30Oct 112021: October 252022: September 302023: October 242024: October 172025: 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 7October 25
2022May 9September 30
2023May 26October 24
2024April 28October 17
2025May 1September 20
2026May 23season not over yet

What these dates mean

The 135 days between the 50% dates in Berlin – May 14 and September 30 – define the core season for planting and harvesting tender crops. The 50% date is May 14, which carries a 50% chance of a light frost later than this date in spring, and the 50% date is September 30, which carries a 50% chance of a light frost earlier than this date in fall. For a cautious approach, the spring light-frost date with a 10% chance of a frost later than the date is May 30, while the fall light-frost date with a 10% chance of a frost earlier than the date is September 15. Hard frost at 28 °F is more damaging than a light frost at 32 °F, so the median hard-frost dates, April 30 and October 10, signal when such risk becomes a 50% possibility.

How to read the probabilities

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

  • Spring: "10% after May 30" 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 15" 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 Berlin, NHNumbered nearest stations: 1 — York Pond, NH — 8 mi; 2 — Pinkham Notch, NH — 14 mi; 3 — Lancaster, NH — 20 mi; 4 — North Conway, NH — 28 mi; 5 — Colebrook, NH — 33 mi.MEVTNH25 mi · 40 km1. York Pond, NH — 8 mi12. Pinkham Notch, NH — 14 mi23. Lancaster, NH — 20 mi34. North Conway, NH — 28 mi45. Colebrook, NH — 33 mi5
  1. York Pond, NH 8 mi (13 km)
  2. Pinkham Notch, NH 14 mi (22 km)
  3. Lancaster, NH 20 mi (31 km)
  4. North Conway, NH 28 mi (44 km)
  5. Colebrook, NH 33 mi (53 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 44.4536, -71.1856.