U.S. Frost Dates by Weather Station

NOAA station USC00273850 · New Hampshire

Frost Dates for Hanover, NH

NOAA weather station Hanover (USC00273850), New Hampshire · elevation 584 ft (178 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostMay 150% chance of a frost after it
  • Typical first fall frostOctober 1350% chance of a frost before it
  • Frost-free season162 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Hanover, NHSpring: a frost after April 21 in 9 years out of 10, after May 1 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 13 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 162 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 1First frost ~Oct 13Frost season at Hanover, NHSpring: a frost after April 21 in 9 years out of 10, after May 1 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 13 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 162 days.JFMAMJJASONDLast frost ~May 1First frost ~Oct 13
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15October 1
50% (typical)May 1October 13
90% (likely)April 21October 29
Frost-free season (32°F, 50% chance)
162 days
Hard frost (28°F), last in spring, 50% chance after
April 19
Hard frost (28°F), first in fall, 50% chance before
October 24

The last 15 years (2006–2020 normals)

Typical last frost May 1 (same as the 30-year normal), typical first fall frost October 16 (3 days later). Frost-free season 167 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 Hanover: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 10, 30% May 6, 40% May 4, 50% May 1, 60% April 30, 70% April 27, 80% April 24, 90% April 21. Observed last spring frost in recent years: 2021 May 7, 2022 May 9, 2023 May 18, 2024 April 27.Spring: last frostChance of a frost after this date10%50%90%May 1May 15May 1Apr 212021: May 72022: May 92023: May 182024: April 27Fall at Hanover: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 5, 30% October 7, 40% October 10, 50% October 13, 60% October 15, 70% October 18, 80% October 22, 90% October 29. Observed first fall frost in recent years: 2021 October 24, 2022 October 3, 2023 October 31, 2024 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 13Oct 292021: October 242022: October 32023: October 312024: October 17
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 24
2022May 9October 3
2023May 18October 31
2024April 27October 17
2025incomplete recordincomplete record
2026incomplete recordseason not over yet

What these dates mean

October 1 marks the cautious fall date for finishing the harvest in Hanover, with only a 10 % chance that a light frost has arrived earlier. Gardeners who wait until this date reduce the risk to tender crops as the season draws to a close.

The 50 % light-frost date of May 1 carries a 50 % chance of a frost later than this date, and October 13 carries a 50 % chance of a frost earlier than this date. Those who prefer a lower risk schedule tender crops to be set out after the cautious spring date of May 15 and to be harvested by the cautious fall date of October 1. The 50 % hard-frost dates are April 19 in spring and October 24 in fall; these indicate when a 28 °F frost has an even chance of happening.

A hard frost at 28°F can injure plant tissue that would usually survive a light frost at 32°F.

How to read the probabilities

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

  • Spring: "10% after May 15" 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 October 1" 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 Hanover, NHNumbered nearest stations: 1 — Newport, NH — 23 mi; 2 — Rochester, VT — 28 mi; 3 — Rutland, VT — 35 mi; 4 — near Barre, VT — 37 mi; 5 — Cornwall, VT — 49 mi.NHNY25 mi · 40 km1. Newport, NH — 23 mi12. Rochester, VT — 28 mi23. Rutland, VT — 35 mi34. near Barre, VT — 37 mi45. Cornwall, VT — 49 mi5
  1. Newport, NH 23 mi (37 km)
  2. Rochester, VT 28 mi (45 km)
  3. Rutland, VT 35 mi (56 km)
  4. near Barre, VT 37 mi (60 km)
  5. Cornwall, VT 49 mi (79 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: 43.7053, -72.2856.