ZIP 48180 Zone 6b

Michigan · USDA zone 6b, average annual extreme minimum -5°F to 0°F.

Nearest qualified station: DETROIT METRO AP, MI US (USW00094847), 3.3 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is April 20. Median first 32°F is October 27. The 50% growing-season length is 188 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%April 6Earlier date. A last 32°F on or after this day is common.
50%April 20Median.
10%May 8Later 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 14Earlier date. A first 32°F on or before this day is uncommon.
50%October 27Median.
90%November 9Later 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%207
50%188
90%167

28°F threshold

10%50%90%
Last, on or afterApril 24April 8March 27
First, on or beforeOctober 27November 7November 22
Season at least232 days212 days193 days

36°F threshold

10%50%90%
Last, on or afterMay 18May 2April 18
First, on or beforeOctober 2October 15October 29
Season at least186 days165 days146 days

Station DETROIT METRO AP, MI US (USW00094847). Completeness flag S, 30 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 192.3 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · Michigan cities