U.S. Frost Dates by Weather Station

NOAA station USW00013781 · Delaware

Frost Dates near Wilmington Manor, DE

NOAA weather station Wilmington New Castle County Airport (USW00013781), Delaware · elevation 79 ft (24 m) · hardiness zone 7b*

Wilmington Manor is the nearest town to the station (1.3 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 21only 1 spring in 10 still has a frost later
  • Typical last frostApril 750% chance of a frost after it
  • Typical first fall frostNovember 150% chance of a frost before it
  • Frost-free season209 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season near Wilmington Manor, DESpring: a frost after March 26 in 9 years out of 10, after April 7 in half of the years, after April 21 in 1 year out of 10. Fall: the first frost comes before October 19 in 1 year out of 10, before November 1 in half of the years, before November 15 in 9 years out of 10. Typical frost-free season: 209 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 7First frost ~Nov 1Frost season near Wilmington Manor, DESpring: a frost after March 26 in 9 years out of 10, after April 7 in half of the years, after April 21 in 1 year out of 10. Fall: the first frost comes before October 19 in 1 year out of 10, before November 1 in half of the years, before November 15 in 9 years out of 10. Typical frost-free season: 209 days.JFMAMJJASONDLast frost ~Apr 7First frost ~Nov 1
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)April 21October 19
50% (typical)April 7November 1
90% (likely)March 26November 15
Frost-free season (32°F, 50% chance)
209 days
Hard frost (28°F), last in spring, 50% chance after
March 27
Hard frost (28°F), first in fall, 50% chance before
November 14

The last 15 years (2006–2020 normals)

Typical last frost April 9 (2 days later than the 30-year normal), typical first fall frost November 3 (2 days later). Frost-free season 209 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 Manor: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 21, 20% April 16, 30% April 12, 40% April 10, 50% April 7, 60% April 4, 70% April 2, 80% March 31, 90% March 26. Observed last spring frost in recent years: 2021 April 3, 2022 April 18, 2023 April 3, 2024 April 22, 2025 April 9, 2026 April 21.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 21Apr 7Mar 262021: April 32022: April 182023: April 32024: April 222025: April 92026: April 21Fall near Wilmington Manor: chance of a frost before this dateFall, chance of a frost before the date: 10% October 19, 20% October 24, 30% October 28, 40% October 31, 50% November 1, 60% November 4, 70% November 7, 80% November 11, 90% November 15. Observed first fall frost in recent years: 2021 November 4, 2022 November 15, 2023 November 1, 2024 November 3, 2025 November 7.Fall: first frostChance of a frost before this date10%50%90%Nov 1Oct 19Nov 1Nov 152021: November 42022: November 152023: November 12024: November 32025: November 7
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 4
2022April 18November 15
2023April 3November 1
2024April 22November 3
2025April 9November 7
2026April 21season not over yet

What these dates mean

The 209 days between the 32°F 50% dates in the Wilmington Manor area define the span in which a light frost is equally likely to have passed or not yet arrived. The median spring date is April 7 and the median fall date is November 1; a gardener can understand that around those points the odds of a light frost are balanced. The hard-frost 28°F median dates are March 27 in spring and November 14 in fall, marking when temperatures of that severity are equally probable.

For a cautious spring plan, the tender-crop window begins after April 21, when there is only a 10 % chance of a later light frost. In fall, the prudent finish date is October 19, with only a 10 % chance that a light frost has already begun. A hard frost matters more than a light frost because the lower temperature of 28°F can cause damage that the milder 32°F light frost typically does not.

How to read the probabilities

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

  • Spring: "10% after April 21" 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 19" 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 Manor, DENumbered nearest stations: 1 — near Wilmington, DE — 8 mi; 2 — Philadelphia, PA — 24 mi; 3 — Seabrook Farms, NJ — 24 mi; 4 — near Oxford, PA — 25 mi; 5 — Phila Franklin Inst, PA — 30 mi.PANJMDDE25 mi · 40 km1. near Wilmington, DE — 8 mi12. Philadelphia, PA — 24 mi23. Seabrook Farms, NJ — 24 mi34. near Oxford, PA — 25 mi45. Phila Franklin Inst, PA — 30 mi5
  1. near Wilmington, DE 8 mi (12 km)
  2. Philadelphia, PA 24 mi (38 km)
  3. Seabrook Farms, NJ 24 mi (39 km)
  4. near Oxford, PA 25 mi (40 km)
  5. Phila Franklin Inst, PA 30 mi (48 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: 39.6728, -75.6008.