U.S. Frost Dates by Weather Station

NOAA station USC00366927 · Pennsylvania

Frost Dates for Phoenixville, PA

NOAA weather station Phoenixville 1 E (USC00366927), Pennsylvania · elevation 85 ft (26 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 4only 1 spring in 10 still has a frost later
  • Typical last frostApril 1850% chance of a frost after it
  • Typical first fall frostOctober 2750% chance of a frost before it
  • Frost-free season192 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Phoenixville, PASpring: a frost after April 3 in 9 years out of 10, after April 18 in half of the years, after May 4 in 1 year out of 10. Fall: the first frost comes before October 12 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 192 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 18First frost ~Oct 27Frost season at Phoenixville, PASpring: a frost after April 3 in 9 years out of 10, after April 18 in half of the years, after May 4 in 1 year out of 10. Fall: the first frost comes before October 12 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 192 days.JFMAMJJASONDLast frost ~Apr 18First frost ~Oct 27
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 4October 12
50% (typical)April 18October 27
90% (likely)April 3November 9
Frost-free season (32°F, 50% chance)
192 days
Hard frost (28°F), last in spring, 50% chance after
April 3
Hard frost (28°F), first in fall, 50% chance before
November 6

The last 15 years (2006–2020 normals)

Typical last frost April 16 (2 days earlier than the 30-year normal), typical first fall frost October 29 (2 days later). Frost-free season 195 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 Phoenixville: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 4, 20% April 29, 30% April 25, 40% April 21, 50% April 18, 60% April 15, 70% April 12, 80% April 7, 90% April 3. Observed last spring frost in recent years: 2024 March 26, 2025 April 9.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 4Apr 18Apr 32024: March 262025: April 9Fall at Phoenixville: chance of a frost before this dateFall, chance of a frost before the date: 10% October 12, 20% October 17, 30% October 20, 40% October 24, 50% October 27, 60% October 31, 70% November 1, 80% November 4, 90% November 9. Observed first fall frost in recent years: 2025 October 27.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 12Oct 27Nov 92025: 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
2021incomplete recordincomplete record
2022incomplete recordincomplete record
2023incomplete recordincomplete record
2024March 26incomplete record
2025April 9October 27
2026incomplete recordseason not over yet

What these dates mean

May 4 is the cautious spring date for Phoenixville, with only a 10% chance of a light frost occurring later, and it gives gardeners a reliable point to set out tender crops. The early spring date of April 3 carries a 90% chance of frost and should be treated as a gamble, while the median April 18 marks the 50% date, meaning a 50% chance of frost later than that day.

October 12 serves as the cautious fall date, offering a 10% chance that a light frost has already arrived and allowing gardeners to finish harvesting tender crops. The median October 27 is the 50% date for fall, indicating equal odds of frost earlier, and November 9 is the risky late date with a 90% chance of frost earlier. The hard-frost 50% dates are April 3 in spring and November 6 in fall; a hard frost at 28 °F can injure plants that survive a light frost at 32 °F, making it 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 4" 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 12" 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 Phoenixville, PANumbered nearest stations: 1 — Phila Franklin Inst, PA — 20 mi; 2 — Philadelphia, PA — 22 mi; 3 — near Wilmington, DE — 24 mi; 4 — Pennsauken, NJ — 27 mi; 5 — New Holland, PA — 31 mi.PANJMDDE25 mi · 40 km1. Phila Franklin Inst, PA — 20 mi12. Philadelphia, PA — 22 mi23. near Wilmington, DE — 24 mi34. Pennsauken, NJ — 27 mi45. New Holland, PA — 31 mi5
  1. Phila Franklin Inst, PA 20 mi (33 km)
  2. Philadelphia, PA 22 mi (36 km)
  3. near Wilmington, DE 24 mi (39 km)
  4. Pennsauken, NJ 27 mi (44 km)
  5. New Holland, PA 31 mi (49 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: 40.1211, -75.4942.