U.S. Frost Dates by Weather Station

NOAA station USC00363028 · Pennsylvania

Frost Dates for Franklin, PA

NOAA weather station Franklin (USC00363028), Pennsylvania · elevation 1015 ft (309 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 20only 1 spring in 10 still has a frost later
  • Typical last frostMay 250% chance of a frost after it
  • Typical first fall frostOctober 2350% chance of a frost before it
  • Frost-free season171 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Franklin, PASpring: a frost after April 20 in 9 years out of 10, after May 2 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 23 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 171 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 2First frost ~Oct 23Frost season at Franklin, PASpring: a frost after April 20 in 9 years out of 10, after May 2 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 23 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 171 days.JFMAMJJASONDLast frost ~May 2First frost ~Oct 23
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 20October 8
50% (typical)May 2October 23
90% (likely)April 20November 4
Frost-free season (32°F, 50% chance)
171 days
Hard frost (28°F), last in spring, 50% chance after
April 21
Hard frost (28°F), first in fall, 50% chance before
November 3

The last 15 years (2006–2020 normals)

Typical last frost April 30 (2 days earlier than the 30-year normal), typical first fall frost October 24 (1 day later). Frost-free season 174 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 Franklin: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 20, 20% May 15, 30% May 9, 40% May 6, 50% May 2, 60% April 30, 70% April 27, 80% April 23, 90% April 20. Observed last spring frost in recent years: 2021 May 10, 2022 April 30, 2023 May 18, 2024 April 26, 2025 April 18, 2026 May 5.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 20May 2Apr 202021: May 102022: April 302023: May 182024: April 262025: April 182026: May 5Fall at Franklin: chance of a frost before this dateFall, chance of a frost before the date: 10% October 8, 20% October 14, 30% October 17, 40% October 20, 50% October 23, 60% October 25, 70% October 29, 80% November 1, 90% November 4. Observed first fall frost in recent years: 2021 November 4, 2022 October 18, 2023 October 23, 2024 October 25, 2025 October 27.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 8Oct 23Nov 42021: November 42022: October 182023: October 232024: October 252025: October 27
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 10November 4
2022April 30October 18
2023May 18October 23
2024April 26October 25
2025April 18October 27
2026May 5season not over yet

What these dates mean

The 171 days between the 50% dates in Franklin—May 2 and October 23—define the span where a light frost (32 °F) is less likely than not, giving gardeners a window in which the odds of a frost are below 50 %.

In spring, the cautious date for setting out tender crops is May 20, when there is only a 10 % chance a light frost will occur later; planting on April 20 carries a 90 % chance of a frost and is a gamble. In fall, the cautious date to finish harvesting tender crops is October 8, with a 10 % chance a light frost has already arrived; targeting November 4 would face a 90 % chance of frost and is risky.

A hard frost at 28 °F—marked by the 50% dates of April 21 in spring and November 3 in fall—creates a greater risk of plant damage than a light frost, because the colder temperature can kill tissue that survives a 32 °F frost.

How to read the probabilities

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

  • Spring: "10% after May 20" 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 8" 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 Franklin, PANumbered nearest stations: 1 — Titusville, PA — 17 mi; 2 — Slippery Rock, PA — 27 mi; 3 — Jamestown, PA — 34 mi; 4 — Linesville, PA — 35 mi; 5 — New Castle, PA — 38 mi.PAOHNY25 mi · 40 km1. Titusville, PA — 17 mi12. Slippery Rock, PA — 27 mi23. Jamestown, PA — 34 mi34. Linesville, PA — 35 mi45. New Castle, PA — 38 mi5
  1. Titusville, PA 17 mi (28 km)
  2. Slippery Rock, PA 27 mi (43 km)
  3. Jamestown, PA 34 mi (54 km)
  4. Linesville, PA 35 mi (57 km)
  5. New Castle, PA 38 mi (62 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: 41.4003, -79.8306.