ZIP 82644 Zone 5a

Wyoming · USDA zone 5a, average annual extreme minimum -20°F to -15°F.

Nearest qualified station: CASPER WWTP, WY US (USC00481569), 4.3 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is May 10. Median first 32°F is September 29. The 50% growing-season length is 138 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 30Earlier date. A last 32°F on or after this day is common.
50%May 10Median.
10%May 24Later 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%September 14Earlier date. A first 32°F on or before this day is uncommon.
50%September 29Median.
90%October 12Later 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%155
50%138
90%118

28°F threshold

10%50%90%
Last, on or afterMay 14May 1April 17
First, on or beforeSeptember 21October 6October 23
Season at least178 days156 days136 days

36°F threshold

10%50%90%
Last, on or afterJune 6May 23May 11
First, on or beforeSeptember 6September 19October 2
Season at least134 days116 days96 days

Station CASPER WWTP, WY US (USC00481569). Completeness flag R, 18 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 1553.6 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · Wyoming cities