U.S. Frost Dates by Weather Station

NOAA station USW00014745 · New Hampshire

Frost Dates for Concord, NH

NOAA weather station Concord Municipal Airport (USW00014745), New Hampshire · elevation 346 ft (106 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 850% 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 zone5bcalculated*

The year at a glance

Frost season at Concord, NHSpring: a frost after April 27 in 9 years out of 10, after May 8 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 3Frost season at Concord, NHSpring: a frost after April 27 in 9 years out of 10, after May 8 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 146 days.JFMAMJJASONDLast frost ~May 8First 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 21
50% (typical)May 8October 3
90% (likely)April 27October 16
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 13

The last 15 years (2006–2020 normals)

Typical last frost May 6 (2 days earlier than the 30-year normal), typical first fall frost October 5 (2 days later). Frost-free season 149 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 Concord: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 18, 30% May 15, 40% May 12, 50% May 8, 60% May 5, 70% May 3, 80% April 30, 90% April 27. Observed last spring frost in recent years: 2021 April 27, 2022 May 11, 2023 May 18, 2024 April 27, 2025 April 21, 2026 May 9.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 8Apr 272021: April 272022: May 112023: May 182024: April 272025: April 212026: May 9Fall at Concord: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 26, 30% September 29, 40% October 1, 50% October 3, 60% October 5, 70% October 7, 80% October 11, 90% October 16. Observed first fall frost in recent years: 2021 October 24, 2022 September 30, 2023 October 24, 2024 October 15, 2025 October 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 21Oct 3Oct 162021: October 242022: September 302023: October 242024: October 152025: October 2
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 11September 30
2023May 18October 24
2024April 27October 15
2025April 21October 2
2026May 9season not over yet

What these dates mean

May 22 is the cautious spring date for light frost in Concord; with only a 10 % chance of frost after that day, a gardener can plan to set out tender crops with minimal risk. The 50% date, May 8, marks the point where a frost is equally likely either side, helping to gauge the uncertainty window.

In the fall, the cautious date is September 21, when there is just a 10 % chance that a frost has already arrived, making it the preferred day to finish harvesting tender crops. The 50% date, October 3, indicates even odds for a frost and defines the middle of the frost-free period.

A hard frost at 28 °F, reflected by the median dates April 27 and October 13, is more damaging than a light frost because it can kill plants rather than merely chill them.

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 21" 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 Concord, NHNumbered nearest stations: 1 — near Manchester, NH — 15 mi; 2 — Epping, NH — 24 mi; 3 — Nashua, NH — 28 mi; 4 — Durham, NH — 28 mi; 5 — Greenland, NH — 36 mi.NHMAMEVT25 mi · 40 km1. near Manchester, NH — 15 mi12. Epping, NH — 24 mi23. Nashua, NH — 28 mi34. Durham, NH — 28 mi45. Greenland, NH — 36 mi5
  1. near Manchester, NH 15 mi (25 km)
  2. Epping, NH 24 mi (39 km)
  3. Nashua, NH 28 mi (45 km)
  4. Durham, NH 28 mi (45 km)
  5. Greenland, NH 36 mi (58 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: 43.1953, -71.5011.