U.S. Frost Dates by Weather Station

NOAA station USC00274556 · New Hampshire

Frost Dates for Lancaster, NH

NOAA weather station Lancaster (USC00274556), New Hampshire · elevation 860 ft (262 m) · hardiness zone 4a*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1850% chance of a frost after it
  • Typical first fall frostSeptember 3050% chance of a frost before it
  • Frost-free season132 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Lancaster, NHSpring: a frost after May 3 in 9 years out of 10, after May 18 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 16 in 1 year out of 10, before September 30 in half of the years, before October 12 in 9 years out of 10. Typical frost-free season: 132 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 18First frost ~Sep 30Frost season at Lancaster, NHSpring: a frost after May 3 in 9 years out of 10, after May 18 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 16 in 1 year out of 10, before September 30 in half of the years, before October 12 in 9 years out of 10. Typical frost-free season: 132 days.JFMAMJJASONDLast frost ~May 18First 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)June 1September 16
50% (typical)May 18September 30
90% (likely)May 3October 12
Frost-free season (32°F, 50% chance)
132 days
Hard frost (28°F), last in spring, 50% chance after
May 5
Hard frost (28°F), first in fall, 50% chance before
October 9

The last 15 years (2006–2020 normals)

Typical last frost May 15 (3 days earlier than the 30-year normal), typical first fall frost October 1 (1 day later). Frost-free season 138 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 Lancaster: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 28, 30% May 24, 40% May 21, 50% May 18, 60% May 15, 70% May 12, 80% May 8, 90% May 3.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 18May 3Fall at Lancaster: chance of a frost before this dateFall, chance of a frost before the date: 10% September 16, 20% September 21, 30% September 25, 40% September 28, 50% September 30, 60% October 1, 70% October 3, 80% October 7, 90% October 12.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 16Sep 30Oct 12
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.

What these dates mean

Setting out tender crops on May 3 carries a 90% chance of a frost later in the season, so planting then is a gamble for Lancaster growers. The 50% date of May 18 marks the point at which there is an even chance of a light frost later, while the hard-frost 50% date of May 5 shows when a 28°F frost is equally likely.

For a lower risk approach, the cautious spring date is June 1, when only 10% of the record years experienced a frost later. In the autumn, the cautious date to finish harvesting tender crops is September 16, with just a 10% chance that a frost arrived earlier. The 50% autumn light-frost date is September 30, which carries a 50% chance of a frost earlier, and the hard-frost 50% date is October 9. A hard frost at 28°F can damage plant tissue more severely than a light frost at 32°F, making those dates especially important for protecting crops.

How to read the probabilities

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

  • Spring: "10% after June 1" 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 16" 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 Lancaster, NHNumbered nearest stations: 1 — York Pond, NH — 12 mi; 2 — Berlin, NH — 20 mi; 3 — Saint Johnsbury, VT — 22 mi; 4 — Pinkham Notch, NH — 23 mi; 5 — Colebrook, NH — 25 mi.MEVT25 mi · 40 km1. York Pond, NH — 12 mi12. Berlin, NH — 20 mi23. Saint Johnsbury, VT — 22 mi34. Pinkham Notch, NH — 23 mi45. Colebrook, NH — 25 mi5
  1. York Pond, NH 12 mi (19 km)
  2. Berlin, NH 20 mi (31 km)
  3. Saint Johnsbury, VT 22 mi (36 km)
  4. Pinkham Notch, NH 23 mi (37 km)
  5. Colebrook, NH 25 mi (41 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: 44.4958, -71.5767.