U.S. Frost Dates by Weather Station

NOAA station USC00079605 · Delaware

Frost Dates near Wilmington, DE

NOAA weather station Wilmington Porter Research (USC00079605), Delaware · elevation 270 ft (82 m) · hardiness zone 7b*

Wilmington is the nearest town to the station (1.9 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 April 24only 1 spring in 10 still has a frost later
  • Typical last frostApril 750% chance of a frost after it
  • Typical first fall frostNovember 450% chance of a frost before it
  • Frost-free season209 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season near Wilmington, DESpring: a frost after March 26 in 9 years out of 10, after April 7 in half of the years, after April 24 in 1 year out of 10. Fall: the first frost comes before October 21 in 1 year out of 10, before November 4 in half of the years, before November 19 in 9 years out of 10. Typical frost-free season: 209 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 7First frost ~Nov 4Frost season near Wilmington, DESpring: a frost after March 26 in 9 years out of 10, after April 7 in half of the years, after April 24 in 1 year out of 10. Fall: the first frost comes before October 21 in 1 year out of 10, before November 4 in half of the years, before November 19 in 9 years out of 10. Typical frost-free season: 209 days.JFMAMJJASONDLast frost ~Apr 7First frost ~Nov 4
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)April 24October 21
50% (typical)April 7November 4
90% (likely)March 26November 19
Frost-free season (32°F, 50% chance)
209 days
Hard frost (28°F), last in spring, 50% chance after
March 29
Hard frost (28°F), first in fall, 50% chance before
November 15

The last 15 years (2006–2020 normals)

Typical last frost April 8 (1 day later than the 30-year normal), typical first fall frost November 8 (4 days later). Frost-free season 214 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 Wilmington: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 24, 20% April 18, 30% April 13, 40% April 10, 50% April 7, 60% April 5, 70% April 2, 80% March 31, 90% March 26. Observed last spring frost in recent years: 2021 April 3, 2022 March 30, 2023 March 30, 2024 March 25, 2025 April 9.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 24Apr 7Mar 262021: April 32022: March 302023: March 302024: March 252025: April 9Fall near Wilmington: chance of a frost before this dateFall, chance of a frost before the date: 10% October 21, 20% October 27, 30% October 30, 40% November 1, 50% November 4, 60% November 7, 70% November 10, 80% November 13, 90% November 19. Observed first fall frost in recent years: 2021 November 14, 2022 November 15, 2023 November 2, 2024 November 13.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 21Nov 4Nov 192021: November 142022: November 152023: November 22024: November 13
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 3November 14
2022March 30November 15
2023March 30November 2
2024March 25November 13
2025April 9incomplete record
2026incomplete recordseason not over yet

What these dates mean

Planting tender crops on March 26 in the Wilmington area carries a 90% chance of a frost later that season, making it a high-risk move. For a more cautious approach, the 10% chance date is April 24, which gardeners can use to set out tender varieties with minimal frost risk. The 50% date is April 7, meaning a 50% chance of a frost later than this date.

In the autumn, the cautious date to finish harvesting tender crops is October 21, when only a 10% chance of an early frost exists. The 50% date is November 4, meaning a 50% chance of a frost earlier than this date. Hard frosts, recorded at 28 °F, are noted on the 50% dates March 29 and November 15; a hard frost can damage plants more severely than a light frost because it reaches a lower temperature threshold.

How to read the probabilities

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

  • Spring: "10% after April 24" 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 21" 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 Wilmington, DENumbered nearest stations: 1 — near Wilmington Manor, DE — 8 mi; 2 — Philadelphia, PA — 18 mi; 3 — Phila Franklin Inst, PA — 23 mi; 4 — Phoenixville, PA — 24 mi; 5 — Seabrook Farms, NJ — 26 mi.PANJMDDE25 mi · 40 km1. near Wilmington Manor, DE — 8 mi12. Philadelphia, PA — 18 mi23. Phila Franklin Inst, PA — 23 mi34. Phoenixville, PA — 24 mi45. Seabrook Farms, NJ — 26 mi5
  1. near Wilmington Manor, DE 8 mi (12 km)
  2. Philadelphia, PA 18 mi (29 km)
  3. Phila Franklin Inst, PA 23 mi (38 km)
  4. Phoenixville, PA 24 mi (39 km)
  5. Seabrook Farms, NJ 26 mi (42 km)

Sources

* Hardiness zone 7b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 39.7739, -75.5414.