Frost dates / District of Columbia / Washington

Frost dates in Washington, DC

The station on this page is NATL ARBORETUM DC, MD US (USC00186350), 2.6 miles from the city point. Population in the Census 2024 estimate is 702,250.

Zone 8aUSDA average annual extreme minimum 10°F to 15°F, from ZIP 20001 (0.4 miles from the city point used on this page).

Median last 32°F is March 29. Median first 32°F is November 8. The 50% growing-season length is 224 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 15	Earlier date. A last 32°F on or after this day is common.
50%	March 29	Median.
10%	April 11	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 26	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 8	Median.
90%	November 23	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%	243
50%	224
90%	205

28°F threshold

	10%	50%	90%
Last, on or after	March 31	March 17	March 2
First, on or before	November 6	November 20	December 7
Season at least	272 days	248 days	229 days

36°F threshold

	10%	50%	90%
Last, on or after	April 28	April 10	March 29
First, on or before	October 14	October 29	November 10
Season at least	219 days	200 days	179 days

Station NATL ARBORETUM DC, MD US (USC00186350). 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 15.2 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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Washington, DC

Zone 8aAverage annual extreme minimum 10°F to 15°F

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

District of Columbia. Nearest qualified station: NATL ARBORETUM DC, MD US (USC00186350), 2.6 miles. Median last 32°F March 29. Median first 32°F November 8. The 50% growing-season length is 224 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 11	March 29	March 15
First 32°F on or before	October 26	November 8	November 23

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.

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Planting calendar

Frost dates for District of Columbia 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.

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