ZIP 20850 Zone 7b

Maryland · USDA zone 7b, average annual extreme minimum 5°F to 10°F.

Nearest qualified station: ROCKVILLE 1 NE, MD US (USC00187705), 1.9 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is April 1. Median first 32°F is November 6. The 50% growing-season length is 219 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.

ProbabilityDateHow to read it
90%March 19Earlier date. A last 32°F on or after this day is common.
50%April 1Median.
10%April 15Later 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.

ProbabilityDateHow to read it
10%October 24Earlier date. A first 32°F on or before this day is uncommon.
50%November 6Median.
90%November 21Later 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 longDays
10%240
50%219
90%200

28°F threshold

10%50%90%
Last, on or afterApril 4March 22March 5
First, on or beforeNovember 5November 19December 6
Season at least267 days243 days224 days

36°F threshold

10%50%90%
Last, on or afterMay 5April 16March 31
First, on or beforeOctober 12October 25November 7
Season at least212 days192 days170 days

Station ROCKVILLE 1 NE, MD US (USC00187705). Completeness flag R, 14 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 134.1 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · Maryland cities