What Hardiness Zone Is Wyoming?

USDA 2023 Plant Hardiness Zone Map · 191 ZIP codes · Data updated 2026-10-28

Quick answer

Wyoming spans USDA hardiness zones 4a–5b on the 2023 Plant Hardiness Zone Map. The most common zone is 5a, covering 58% of Wyoming's ZIP codes, followed by zone 4b (23%). Zone 5a means the coldest night of an average winter reaches −20°F to −15°F (−29°C to −26°C). Enter your ZIP code for your exact zone.

Wyoming hardiness zones by share of ZIP codes

Zone 4a5% · 10 ZIPs

Zone 4b23% · 43 ZIPs

Zone 5a58% · 110 ZIPs

Zone 5b15% · 28 ZIPs

What the zones mean for Wyoming gardeners

Coldest and warmest towns: among towns with NOAA weather stations, Daniel Fish Hatchery (7,341 ft) is in zone 4a, while Carpenter 3N (5,437 ft) is in zone 5b. That is a difference of about 15°F in the coldest night of a typical winter.
Same zone, different frost dates: within zone 5a, the median last spring frost ranges from May 6 at Deaver to June 14 at Alta 1 NNW, 39 days apart. Your zone tells you which perennials survive winter; your frost dates tell you when to plant.

Typical frost dates in each Wyoming zone

Medians across NOAA weather stations in each zone. Colder zones usually have later spring frosts, but local terrain can shift the dates by weeks.

Zone	Last spring frost	First fall frost	Stations
4a	June 9	September 4	3
4b	May 21	September 23	11
5a	May 18	September 24	34
5b	May 21	September 24	5

Hardiness zones for Wyoming cities

Zones at the National Weather Service stations, mostly city airports, with their median frost dates.


Lander 11 SSE	5a	−20°F to −15°F	5,773	May 13	Oct 2
Moose 1 NNE	4a	−30°F to −25°F	6,466	Jun 24	Aug 28
Torrington Municipal Airport	5a	−20°F to −15°F	4,205	May 11	Sep 29

Hardiness zones for 61 towns in Wyoming

Each NOAA weather station is shown with the USDA zone of the nearest ZIP code (within 8 miles). Coldest night is the zone's range for the average annual extreme minimum temperature. Click a column to sort.

Filter by town


Afton	5b	−15°F to −10°F	6,248	Jun 20	Sep 1
Alta 1 NNW	5a	−20°F to −15°F	6,440	Jun 14	Sep 11
Archer	5b	−15°F to −10°F	6,010	May 21	Sep 24
Baggs	4b	−25°F to −20°F	6,319	Jun 1	Sep 18
Basin	4b	−25°F to −20°F	3,840	Apr 28	Oct 10
Bedford 3 SE	5b	−15°F to −10°F	6,355	Any month	Any month
Bondurant	4b	−25°F to −20°F	6,693	Any month	Any month
Buffalo	5a	−20°F to −15°F	4,639	May 24	Sep 21
Burgess Junction	4b	−25°F to −20°F	8,060	Any month	Any month
Carpenter 3N	5b	−15°F to −10°F	5,437	May 14	Sep 26
Casper 1SW	5a	−20°F to −15°F	5,143	May 12	Oct 1
Casper Wwtp	5a	−20°F to −15°F	5,097	May 10	Sep 29
Centennial 1NE	5a	−20°F to −15°F	8,170	Jun 2	Sep 19
Cheyenne WFO	5b	−15°F to −10°F	6,119	May 14	Oct 1
Chugwater	5a	−20°F to −15°F	5,304	May 18	Sep 24
Daniel Fish Hatchery	4a	−30°F to −25°F	7,341	Any month	Any month
Dayton	5a	−20°F to −15°F	3,920	May 24	Sep 18
Deaver	5a	−20°F to −15°F	4,105	May 6	Oct 1
Devils Tower #2	4b	−25°F to −20°F	3,862	May 23	Sep 20
Diversion Dam	5a	−20°F to −15°F	5,578	May 21	Sep 20
Dubois	4b	−25°F to −20°F	6,955	Any month	Any month
Elk Mountain	5a	−20°F to −15°F	7,265	May 28	Sep 13
Emblem	5a	−20°F to −15°F	4,448	May 12	Sep 28
Farson 2NNE	4a	−30°F to −25°F	6,620	Any month	Any month
Glendo Rsvr Usbr	5a	−20°F to −15°F	4,780	May 9	Oct 5
Greybull	4b	−25°F to −20°F	3,787	May 11	Sep 23
Guernsey 2NW	5a	−20°F to −15°F	4,480	May 7	Oct 6
Heart Mountain	5a	−20°F to −15°F	4,790	May 15	Sep 25
Hulett	5a	−20°F to −15°F	3,758	May 17	Sep 23
Jeffrey City	4b	−25°F to −20°F	6,319	Jun 1	Sep 13
Kaycee	5a	−20°F to −15°F	4,660	May 18	Sep 25
Kemmerer 2N	4b	−25°F to −20°F	6,937	Any month	Any month
La Barge	4a	−30°F to −25°F	6,598	Jun 9	Sep 4
Lance Creek 11NNE	4b	−25°F to −20°F	4,204	May 17	Sep 25
Lander 11 SSE	5a	−20°F to −15°F	5,773	May 13	Oct 2
Laramie 2 NW	4a	−30°F to −25°F	7,140	Jun 7	Sep 4
Leiter 9N	5a	−20°F to −15°F	4,160	May 14	Sep 30
Lingle 2WSW	5a	−20°F to −15°F	4,158	May 20	Sep 22
Lovell	5a	−20°F to −15°F	3,847	May 9	Sep 29
Midwest	5a	−20°F to −15°F	4,860	May 22	Sep 22
Moose	4b	−25°F to −20°F	6,444	Jun 20	Aug 31
Moose 1 NNE	4a	−30°F to −25°F	6,466	Jun 24	Aug 28
Mountain View	5b	−15°F to −10°F	6,800	Jun 14	Sep 9
Old Fort Laramie	5a	−20°F to −15°F	4,250	May 14	Sep 26
Phillips	5a	−20°F to −15°F	4,982	May 21	Sep 21
Pine Bluffs 1ESE	5a	−20°F to −15°F	5,058	May 10	Oct 1
Powder River #2	5a	−20°F to −15°F	5,700	May 23	Sep 20
Riverton	5a	−20°F to −15°F	4,955	May 12	Sep 24
Saratoga	5a	−20°F to −15°F	6,790	Jun 2	Sep 12
Sheridan Field Station	5a	−20°F to −15°F	3,750	May 18	Sep 24
Shoshoni	4b	−25°F to −20°F	4,837	May 7	Oct 3
Story	5a	−20°F to −15°F	5,168	May 24	Sep 23
Sundance	4b	−25°F to −20°F	4,695	May 21	Sep 25
Sunshine 3NE	4b	−25°F to −20°F	6,224	Any month	Any month
Tensleep 16SSE	5a	−20°F to −15°F	4,680	May 22	Sep 18
Thermopolis 9NE	4b	−25°F to −20°F	4,282	May 24	Sep 16
Torrington Municipal Airport	5a	−20°F to −15°F	4,205	May 11	Sep 29
Upton	4b	−25°F to −20°F	4,320	May 20	Sep 23
Wapiti 1WSW	5a	−20°F to −15°F	5,558	May 27	Sep 25
Wright 12W	5a	−20°F to −15°F	5,020	May 25	Sep 23
Yoder 5 W	5a	−20°F to −15°F	4,330	May 15	Sep 27

Frequently asked questions

What hardiness zone is Wyoming?

Wyoming is in USDA hardiness zones 4a–5b on the 2023 USDA Plant Hardiness Zone Map. Zone 5a is the most common, covering 58% of Wyoming's ZIP codes, and zone 4b covers 23%. Enter your ZIP code for your exact zone.

What does zone 5a mean?

Zone 5a means the average annual extreme minimum temperature, the coldest night of a typical winter, is −20°F to −15°F (−29°C to −26°C). Perennials, shrubs and trees rated for zone 5a or colder should survive winter there.

What is the coldest hardiness zone in Wyoming?

Zone 4a is the coldest zone mapped in Wyoming, found around Daniel Fish Hatchery, and zone 5b is the warmest, found around Carpenter 3N.

Did Wyoming's hardiness zones change in 2023?

The USDA released a new Plant Hardiness Zone Map in November 2023, based on 1991–2020 temperatures instead of 1976–2005. About half of the United States shifted half a zone warmer. Check your ZIP code here, because plant tags and older books may still list your 2012 zone.

When should I plant in zone 5a?

Hardiness zones don't set planting dates; frost dates do. Inside zone 5a in Wyoming, the median last spring frost varies from May 6 to June 14. Look up your local frost dates and plant tender crops such as tomatoes after the 10%-risk last-frost date.

Zone and frost dates: use both

Your hardiness zone answers one question: will this plant survive the winter here? Choose perennials, shrubs, trees and bulbs rated for your zone or a colder one. For vegetables and annuals, what matters is the length of the frost-free season. See Wyoming frost dates by town, or get a planting calendar for your ZIP code with start-indoors, transplant and sowing dates for 30 crops.

Sources and method

Zones are from the USDA 2023 Plant Hardiness Zone Map ZIP-code files published by the PRISM Climate Group, Oregon State University, based on 1991–2020 minimum temperatures. ZIP codes are assigned to states by USPS prefix. Town zones use the ZIP code nearest each NOAA 1991–2020 Climate Normals station. This is an independent tool, not an official USDA site. Full methodology.