ZIP 80501 Zone 5b

Colorado · USDA zone 5b, average annual extreme minimum -15°F to -10°F.

Nearest qualified station: LONGMONT 2 ESE, CO US (USC00055116), 1.3 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is May 7. Median first 32°F is October 5. The 50% growing-season length is 151 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 24Earlier date. A last 32°F on or after this day is common.
50%May 7Median.
10%May 22Later 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 23Earlier date. A first 32°F on or before this day is uncommon.
50%October 5Median.
90%October 16Later 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%169
50%151
90%131

28°F threshold

10%50%90%
Last, on or afterMay 12April 28April 11
First, on or beforeSeptember 30October 12October 25
Season at least189 days169 days151 days

36°F threshold

10%50%90%
Last, on or afterJune 2May 18May 5
First, on or beforeSeptember 14September 28October 8
Season at least151 days132 days111 days

Station LONGMONT 2 ESE, CO US (USC00055116). Completeness flag R, 17 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 1508.8 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · Colorado cities