U.S. Frost Dates by Weather Station

NOAA station USW00014736 · Pennsylvania

Frost Dates near Martinsburg, PA

NOAA weather station Altoona Blair County Airport (USW00014736), Pennsylvania · elevation 1480 ft (451 m) · hardiness zone 6b*

Martinsburg is the nearest town to the station (1.1 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2350% chance of a frost after it
  • Typical first fall frostOctober 2150% chance of a frost before it
  • Frost-free season177 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season near Martinsburg, PASpring: a frost after April 8 in 9 years out of 10, after April 23 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 21 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 177 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 23First frost ~Oct 21Frost season near Martinsburg, PASpring: a frost after April 8 in 9 years out of 10, after April 23 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 21 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 177 days.JFMAMJJASONDLast frost ~Apr 23First frost ~Oct 21
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 11October 5
50% (typical)April 23October 21
90% (likely)April 8November 4
Frost-free season (32°F, 50% chance)
177 days
Hard frost (28°F), last in spring, 50% chance after
April 11
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 22 (1 day earlier than the 30-year normal), typical first fall frost October 23 (2 days later). Frost-free season 184 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 near Martinsburg: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 5, 30% April 30, 40% April 27, 50% April 23, 60% April 20, 70% April 17, 80% April 13, 90% April 8. Observed last spring frost in recent years: 2021 April 23, 2022 April 30, 2023 April 25, 2024 April 22, 2025 April 17, 2026 May 3.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 23Apr 82021: April 232022: April 302023: April 252024: April 222025: April 172026: May 3Fall near Martinsburg: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 11, 30% October 14, 40% October 18, 50% October 21, 60% October 23, 70% October 26, 80% October 30, 90% November 4. Observed first fall frost in recent years: 2021 November 2, 2022 October 9, 2023 October 31, 2024 October 18, 2025 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 21Nov 42021: November 22022: October 92023: October 312024: October 182025: 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
2021April 23November 2
2022April 30October 9
2023April 25October 31
2024April 22October 18
2025April 17October 17
2026May 3season not over yet

What these dates mean

October 5 is the cautious fall date for finishing the harvest in the Martinsburg area, because there is only a 10% chance that a light frost has arrived earlier. Gardeners who wait until the 50% fall date of October 21 know that the odds of a frost are even, while a 90% chance of frost earlier than November 4 makes planting tender crops that late a gamble.

The 50% spring date of April 23 marks the point where a light frost is equally likely to occur later, providing a reference for timing. A cautious spring plan uses May 11, the date with only a 10% chance of a frost later, whereas planting on April 8 bears a 90% chance and is risky.

Hard frost at 28°F, represented by the 50% dates of April 11 in spring and November 1 in fall, matters more than a 32°F light frost because it can injure or kill plants that would otherwise survive milder temperatures.

How to read the probabilities

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

  • Spring: "10% after May 11" 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 5" 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 Martinsburg, PANumbered nearest stations: 1 — Altoona, PA — 16 mi; 2 — Everett, PA — 20 mi; 3 — Ebensburg, PA — 25 mi; 4 — near Patton, PA — 27 mi; 5 — State College, PA — 42 mi.MD25 mi · 40 km1. Altoona, PA — 16 mi12. Everett, PA — 20 mi23. Ebensburg, PA — 25 mi34. near Patton, PA — 27 mi45. State College, PA — 42 mi5
  1. Altoona, PA 16 mi (25 km)
  2. Everett, PA 20 mi (32 km)
  3. Ebensburg, PA 25 mi (40 km)
  4. near Patton, PA 27 mi (44 km)
  5. State College, PA 42 mi (67 km)

Sources

* Hardiness zone 6b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.2964, -78.3203.