U.S. Frost Dates by Weather Station

NOAA station USC00365109 · Pennsylvania

Frost Dates for Lock Haven, PA

NOAA weather station Lock Haven Sewage Plant (USC00365109), Pennsylvania · elevation 566 ft (173 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season173 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Lock Haven, PASpring: a frost after April 16 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 20 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 173 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 20Frost season at Lock Haven, PASpring: a frost after April 16 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 20 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 173 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 20
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15October 5
50% (typical)April 30October 20
90% (likely)April 16November 1
Frost-free season (32°F, 50% chance)
173 days
Hard frost (28°F), last in spring, 50% chance after
April 16
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 28 (2 days earlier than the 30-year normal), typical first fall frost October 23 (3 days later). Frost-free season 177 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 Lock Haven: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 9, 30% May 6, 40% May 2, 50% April 30, 60% April 26, 70% April 23, 80% April 20, 90% April 16. Observed last spring frost in recent years: 2022 April 30, 2023 May 18, 2024 April 26, 2025 April 18, 2026 April 22.Spring: last frostChance of a frost after this date10%50%90%May 1May 15Apr 30Apr 162022: April 302023: May 182024: April 262025: April 182026: April 22Fall at Lock Haven: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 10, 30% October 13, 40% October 17, 50% October 20, 60% October 23, 70% October 26, 80% October 29, 90% November 1. Observed first fall frost in recent years: 2023 November 2, 2024 October 27, 2025 October 18.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 20Nov 12023: November 22024: October 272025: October 18
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
2022April 30incomplete record
2023May 18November 2
2024April 26October 27
2025April 18October 18
2026April 22season not over yet

What these dates mean

Setting out tender crops on April 16 in Lock Haven carries a 90% chance of a light frost, making it a gamble for gardeners.

The 50% light-frost dates are April 30 and October 20; each represents a 50% chance of a light frost later than April 30 in spring or earlier than October 20 in fall. The 50% hard-frost dates are April 16 and November 1, marking the point where a hard frost is as likely as not.

A cautious plan would wait until May 15 to set out tender crops in spring and until October 5 to finish harvesting them in fall, each date carrying only a 10% chance of a light frost. A hard frost at 28 °F can damage plants that survive a light frost at 32 °F, so it is a more severe threat.

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 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 Lock Haven, PANumbered nearest stations: 1 — Renovo, PA — 21 mi; 2 — Williamsport, PA — 28 mi; 3 — State College, PA — 33 mi; 4 — Stevenson Dam, PA — 36 mi; 5 — Lewistown, PA — 38 mi.PA25 mi · 40 km1. Renovo, PA — 21 mi12. Williamsport, PA — 28 mi23. State College, PA — 33 mi34. Stevenson Dam, PA — 36 mi45. Lewistown, PA — 38 mi5
  1. Renovo, PA 21 mi (34 km)
  2. Williamsport, PA 28 mi (45 km)
  3. State College, PA 33 mi (52 km)
  4. Stevenson Dam, PA 36 mi (58 km)
  5. Lewistown, 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: 41.1311, -77.4336.