Frost dates / Maryland / Frederick

Frost dates in Frederick, MD

The station on this page is FREDERICK POLICE BRKS, MD US (USC00183348), 1.8 miles from the city point. Population in the Census 2024 estimate is 89,537.

Zone 7bUSDA average annual extreme minimum 5°F to 10°F, from ZIP 21705 (1.8 miles from the city point used on this page).

Median last 32°F is April 2. Median first 32°F is November 6. The 50% growing-season length is 218 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 17	Earlier date. A last 32°F on or after this day is common.
50%	April 2	Median.
10%	April 15	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 23	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 6	Median.
90%	November 24	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%	239
50%	218
90%	196

28°F threshold

	10%	50%	90%
Last, on or after	April 4	March 21	March 3
First, on or before	November 6	November 21	December 11
Season at least	271 days	245 days	223 days

36°F threshold

	10%	50%	90%
Last, on or after	May 2	April 15	March 31
First, on or before	October 9	October 24	November 6
Season at least	213 days	193 days	170 days

Station FREDERICK POLICE BRKS, MD US (USC00183348). Completeness flag R, 12 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 115.8 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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Frederick, MD

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

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

Maryland. Nearest qualified station: FREDERICK POLICE BRKS, MD US (USC00183348), 1.8 miles. Median last 32°F April 2. Median first 32°F November 6. The 50% growing-season length is 218 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 15	April 2	March 17
First 32°F on or before	October 23	November 6	November 24

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 Maryland 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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