U.S. Frost Dates by Weather Station

NOAA station USW00004787 · Pennsylvania

Frost Dates for Dubois, PA

NOAA weather station Dubois Jefferson County Airport (USW00004787), Pennsylvania · elevation 1814 ft (553 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 23only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 1450% chance of a frost before it
  • Frost-free season160 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Dubois, PASpring: a frost after April 19 in 9 years out of 10, after May 6 in half of the years, after May 23 in 1 year out of 10. Fall: the first frost comes before September 29 in 1 year out of 10, before October 14 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 160 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 14Frost season at Dubois, PASpring: a frost after April 19 in 9 years out of 10, after May 6 in half of the years, after May 23 in 1 year out of 10. Fall: the first frost comes before September 29 in 1 year out of 10, before October 14 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 160 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 14
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 23September 29
50% (typical)May 6October 14
90% (likely)April 19November 1
Frost-free season (32°F, 50% chance)
160 days
Hard frost (28°F), last in spring, 50% chance after
April 24
Hard frost (28°F), first in fall, 50% chance before
October 28

The last 15 years (2006–2020 normals)

Typical last frost May 5 (1 day earlier than the 30-year normal), typical first fall frost October 19 (5 days later). Frost-free season 163 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 Dubois: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 23, 20% May 17, 30% May 13, 40% May 9, 50% May 6, 60% May 2, 70% April 29, 80% April 24, 90% April 19. Observed last spring frost in recent years: 2021 May 9, 2022 April 29, 2023 April 25, 2024 April 22, 2025 April 17, 2026 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 23May 6Apr 192021: May 92022: April 292023: April 252024: April 222025: April 172026: May 12Fall at Dubois: chance of a frost before this dateFall, chance of a frost before the date: 10% September 29, 20% October 3, 30% October 7, 40% October 11, 50% October 14, 60% October 17, 70% October 20, 80% October 25, 90% November 1. Observed first fall frost in recent years: 2021 November 2, 2022 October 20, 2023 October 23, 2024 October 25, 2025 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 29Oct 14Nov 12021: November 22022: October 202023: October 232024: October 252025: 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
2021May 9November 2
2022April 29October 20
2023April 25October 23
2024April 22October 25
2025April 17October 17
2026May 12season not over yet

What these dates mean

September 29 is the cautious fall date in Dubois for finishing the harvest, reflecting only a 10 % chance that a light frost has arrived earlier.

The 50 % dates—May 6 for spring and October 14 for fall—are the points where a light frost (32 °F) is equally likely to occur before or after; they serve as reference markers rather than frost thresholds. For hard frost the median dates are April 24 in spring and October 28 in fall, indicating when a 28 °F frost is as probable as not. These percentages are drawn from 25 years of NOAA normals.

A cautious planting plan in spring uses the May 23 date, which carries a 10 % chance of a later light frost, while the fall plan relies on the September 29 date to avoid an early frost. A hard frost matters more than a light frost because the colder 28 °F temperature can damage plant tissue that would survive a 32 °F event.

How to read the probabilities

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

  • Spring: "10% after May 23" 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 29" 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 Dubois, PANumbered nearest stations: 1 — Ridgway, PA — 18 mi; 2 — Kane, PA — 35 mi; 3 — near Patton, PA — 41 mi; 4 — Indiana, PA — 42 mi; 5 — Bradford, PA — 45 mi.NY25 mi · 40 km1. Ridgway, PA — 18 mi12. Kane, PA — 35 mi23. near Patton, PA — 41 mi34. Indiana, PA — 42 mi45. Bradford, PA — 45 mi5
  1. Ridgway, PA 18 mi (30 km)
  2. Kane, PA 35 mi (56 km)
  3. near Patton, PA 41 mi (65 km)
  4. Indiana, PA 42 mi (67 km)
  5. Bradford, PA 45 mi (73 km)

Sources

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

Station coordinates: 41.1783, -78.8989.