When is the last frost in Cheyenne, WY?

The average (50% probability) last spring frost in Cheyenne is May 12, based on NOAA 1991–2020 normals. A 1-in-10 risk remains until May 26.

When is the first frost in Cheyenne?

The average first fall frost in Cheyenne is October 1, with a growing season of about 141 days.

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Cheyenne, Wyoming frost dates

Average last spring frost: May 12. Average first fall frost: October 1. That gives a growing season of about 141 days. For frost-tender plants, a safer planting date is May 26, after which a freeze happens in only 1 year in 10.

Last frost (50%)

May 12

1-in-10 risk after May 26

First frost (50%)

Oct 1

1-in-10 risk before Sep 18

Growing season

141 days

median frost-free days

Hard freeze (28°F)

May 2

median last 28°F in spring

Frost risk by date

Chance of frost	Spring: frost after	Fall: frost before
90%	May 1	October 14
70%	May 8	October 7
50%	May 12	October 1
30%	May 18	September 27
10%	May 26	September 18

Read the spring column like this: there is a 10% chance of a 32°F freeze after May 26. These are NOAA probabilities for the Cheyenne weather station (USW00024018, elevation 1868 m), 1991–2020.

Cheyenne vegetable planting calendar

Dates count from the 50% last-frost date (May 12). For tomatoes, peppers and other frost-tender crops, waiting until the 10% date (May 26) is the cautious choice.

Crop	Start seeds indoors	Plant out
Beans	Apr 21	May 19 (usually sown directly in the garden)
Broccoli	Mar 3	Apr 14
Brussels sprouts	Mar 3	Apr 14
Cabbage	Feb 24	Apr 7
Cauliflower	Mar 17	Apr 28
Sweet corn	Apr 14	May 12 (usually sown directly in the garden)
Cucumbers	Apr 28	May 19
Kale	Feb 24	Apr 7
Leeks	Jan 27	Apr 7
Lettuce	Mar 24	Apr 28
Melons	May 5	May 26
Onions	Jan 20	Mar 31 (from seed; sets and transplants go out at the same time)
Peas	Mar 17	Apr 14 (usually sown directly in the garden)
Peppers	Mar 31	May 26
Squash	May 5	May 26
Tomatoes	Mar 17	May 12

Offsets from Oregon State University Extension's seed-starting table. "Plant out" means transplant, or sow directly for crops usually grown from seed.

Fall frost and season extension

The first fall freeze usually arrives around October 1. There's a 1-in-10 chance it comes before September 18. Harvest tender crops such as basil, tomatoes, peppers and squash before then, or cover them on cold nights. Cool-season crops like kale, cabbage and Brussels sprouts handle light frost, and often taste sweeter after it. A hard freeze (28°F) typically comes around October 11.

Nearby cities

City	Last frost (50%)	First frost (50%)	Distance
Denver, CO	May 5	Oct 9	~147 km
Colorado Springs, CO	May 3	Oct 8	~260 km
Pueblo, CO	Apr 30	Oct 9	~319 km
Rapid City, SD	May 12	Oct 1	~353 km
Grand Junction, CO	Apr 28	Oct 16	~384 km
Salt Lake City, UT	Apr 8	Oct 31	~600 km

More: all Wyoming frost dates