Frost dates / Wyoming / Cheyenne

Frost dates in Cheyenne, WY

The station on this page is CHEYENNE WFO, WY US (USC00481676), 1.8 miles from the city point. Population in the Census 2024 estimate is 65,704.

Zone 5bUSDA average annual extreme minimum -15°F to -10°F, from ZIP 82005 (4.2 miles from the city point used on this page).

Median last 32°F is May 14. Median first 32°F is October 1. The 50% growing-season length is 139 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%	May 3	Earlier date. A last 32°F on or after this day is common.
50%	May 14	Median.
10%	May 28	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%	September 17	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 1	Median.
90%	October 14	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%	155
50%	139
90%	119

28°F threshold

	10%	50%	90%
Last, on or after	May 17	May 3	April 20
First, on or before	September 27	October 10	October 23
Season at least	175 days	157 days	137 days

36°F threshold

	10%	50%	90%
Last, on or after	June 7	May 26	May 13
First, on or before	September 11	September 24	October 5
Season at least	136 days	120 days	101 days

Station CHEYENNE WFO, WY US (USC00481676). 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 1865.1 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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Cheyenne, WY

Zone 5bAverage annual extreme minimum -15°F to -10°F

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

Wyoming. Nearest qualified station: CHEYENNE WFO, WY US (USC00481676), 1.8 miles. Median last 32°F May 14. Median first 32°F October 1. The 50% growing-season length is 139 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 28	May 14	May 3
First 32°F on or before	September 17	October 1	October 14

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 Wyoming 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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