U.S. Frost Dates by Weather Station

NOAA station USC00361354 · Pennsylvania

Frost Dates for Chambersburg, PA

NOAA weather station Chambersburg 1 ESE (USC00361354), Pennsylvania · elevation 640 ft (195 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 5only 1 spring in 10 still has a frost later
  • Typical last frostApril 1850% chance of a frost after it
  • Typical first fall frostOctober 2550% chance of a frost before it
  • Frost-free season188 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Chambersburg, PASpring: a frost after April 3 in 9 years out of 10, after April 18 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 25 in half of the years, before November 8 in 9 years out of 10. Typical frost-free season: 188 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 18First frost ~Oct 25Frost season at Chambersburg, PASpring: a frost after April 3 in 9 years out of 10, after April 18 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 25 in half of the years, before November 8 in 9 years out of 10. Typical frost-free season: 188 days.JFMAMJJASONDLast frost ~Apr 18First frost ~Oct 25
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 5October 10
50% (typical)April 18October 25
90% (likely)April 3November 8
Frost-free season (32°F, 50% chance)
188 days
Hard frost (28°F), last in spring, 50% chance after
April 4
Hard frost (28°F), first in fall, 50% chance before
November 6

The last 15 years (2006–2020 normals)

Typical last frost April 17 (1 day earlier than the 30-year normal), typical first fall frost October 28 (3 days later). Frost-free season 193 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 Chambersburg: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 5, 20% April 30, 30% April 25, 40% April 21, 50% April 18, 60% April 15, 70% April 11, 80% April 8, 90% April 3. Observed last spring frost in recent years: 2023 April 25, 2024 March 26, 2025 April 17.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 5Apr 18Apr 32023: April 252024: March 262025: April 17Fall at Chambersburg: chance of a frost before this dateFall, chance of a frost before the date: 10% October 10, 20% October 15, 30% October 19, 40% October 22, 50% October 25, 60% October 28, 70% November 1, 80% November 3, 90% November 8. Observed first fall frost in recent years: 2022 November 9, 2023 November 2, 2024 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 10Oct 25Nov 82022: November 92023: November 22024: 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
2021incomplete recordincomplete record
2022incomplete recordNovember 9
2023April 25November 2
2024March 26October 17
2025April 17no data
2026no dataseason not over yet

What these dates mean

Planting tender crops on April 3 in Chambersburg is a gamble because a frost later than this date occurs with a 90% chance. Such a high probability makes early sowing risky for sensitive seedlings.

The median light-frost dates are April 18 for spring and October 25 for fall; each marks the point at which a frost is equally likely to have occurred or not. A cautious spring plan uses the May 5 date, which carries only a 10% chance of a later frost, while a cautious fall plan finishes tender harvest by October 10, which also has a 10% chance of an earlier frost.

Hard frost, defined at 28 °F, is more damaging than a light 32 °F frost, so the 50% hard-frost dates of April 4 and November 6 signal when such severe cold becomes equally probable.

How to read the probabilities

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

  • Spring: "10% after May 5" 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 10" 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 Chambersburg, PANumbered nearest stations: 1 — Shippensburg, PA — 11 mi; 2 — Biglerville, PA — 20 mi; 3 — Emmitsburg, MD — 26 mi; 4 — Everett, PA — 39 mi; 5 — near Martinsburg, WV — 41 mi.PAMDWV25 mi · 40 km1. Shippensburg, PA — 11 mi12. Biglerville, PA — 20 mi23. Emmitsburg, MD — 26 mi34. Everett, PA — 39 mi45. near Martinsburg, WV — 41 mi5
  1. Shippensburg, PA 11 mi (17 km)
  2. Biglerville, PA 20 mi (33 km)
  3. Emmitsburg, MD 26 mi (42 km)
  4. Everett, PA 39 mi (62 km)
  5. near Martinsburg, WV 41 mi (66 km)

Sources

* Hardiness zone 7a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 39.9353, -77.6394.