Frost dates / Delaware / Wilmington

Frost dates in Wilmington, DE

The station on this page is WILMINGTON PORTER RSCH, DE US (USC00079605), 2.7 miles from the city point. Population in the Census 2024 estimate is 73,176.

Zone 7bUSDA average annual extreme minimum 5°F to 10°F, from ZIP 19801 (1 miles from the city point used on this page).

Median last 32°F is April 7. Median first 32°F is November 4. The 50% growing-season length is 209 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	March 26	Earlier date. A last 32°F on or after this day is common.
50%	April 7	Median.
10%	April 24	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	October 21	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 4	Median.
90%	November 19	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	229
50%	209
90%	189

28°F threshold

	10%	50%	90%
Last, on or after	April 10	March 29	March 13
First, on or before	November 1	November 15	December 2
Season at least	254 days	232 days	213 days

36°F threshold

	10%	50%	90%
Last, on or after	May 7	April 20	April 6
First, on or before	October 9	October 24	November 6
Season at least	204 days	185 days	165 days

Station WILMINGTON PORTER RSCH, DE US (USC00079605). Completeness flag S, 29 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 82.3 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Check a crop against this station

Wilmington, DE

Zone 7bAverage annual extreme minimum 5°F to 10°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Delaware. Nearest qualified station: WILMINGTON PORTER RSCH, DE US (USC00079605), 2.7 miles. Median last 32°F April 7. Median first 32°F November 4. The 50% growing-season length is 209 days.

Open the ZIP page

32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 24	April 7	March 26
First 32°F on or before	October 21	November 4	November 19

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

A wall calendar surrounded by vegetables, herbs, seed packets, and watering cans.

Planting calendar

Frost dates for Delaware are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

Date checks use your device’s calendar and appear after the page loads.