What Hardiness Zone Is Montana?

Q: What hardiness zone is Montana?

Montana is in USDA hardiness zones 3b–6b on the 2023 USDA Plant Hardiness Zone Map. Zone 4b is the most common, covering 32% of Montana's ZIP codes, and zone 5a covers 28%. Enter your ZIP code for your exact zone.

Q: What does zone 4b mean?

Zone 4b means the average annual extreme minimum temperature, the coldest night of a typical winter, is −25°F to −20°F (−32°C to −29°C). Perennials, shrubs and trees rated for zone 4b or colder should survive winter there.

Q: What is the coldest hardiness zone in Montana?

Zone 3b is the coldest zone mapped in Montana, found around Opheim 12 SSE, and zone 6b is the warmest, found around Heron 2 NW.

Q: Did Montana'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.

Q: When should I plant in zone 4b?

Hardiness zones don't set planting dates; frost dates do. Inside zone 4b in Montana, the median last spring frost varies from May 5 to June 18. Look up your local frost dates and plant tender crops such as tomatoes after the 10%-risk last-frost date.

USDA 2023 Plant Hardiness Zone Map · 399 ZIP codes · Data updated 2026-10-28

Quick answer

Montana spans USDA hardiness zones 3b–6b on the 2023 Plant Hardiness Zone Map. The most common zone is 4b, covering 32% of Montana's ZIP codes, followed by zone 5a (28%). Zone 4b means the coldest night of an average winter reaches −25°F to −20°F (−32°C to −29°C). Enter your ZIP code for your exact zone.

Montana hardiness zones by share of ZIP codes

Zone 3b6% · 25 ZIPs

Zone 4a18% · 71 ZIPs

Zone 4b32% · 129 ZIPs

Zone 5a28% · 111 ZIPs

Zone 5b8% · 32 ZIPs

Zone 6a8% · 30 ZIPs

Zone 6b<1% · 1 ZIP

What the zones mean for Montana gardeners

Coldest and warmest towns: among towns with NOAA weather stations, Opheim 12 SSE (2,936 ft) is in zone 3b, while Heron 2 NW (2,240 ft) is in zone 6b. That is a difference of about 30°F in the coldest night of a typical winter.
Same zone, different frost dates: within zone 4b, the median last spring frost ranges from May 5 at Mosby 4 ENE to June 18 at Tizer Gardens, 44 days apart. Your zone tells you which perennials survive winter; your frost dates tell you when to plant.

Typical frost dates in each Montana 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
3b	May 24	September 15	9
4a	May 21	September 20	22
4b	May 21	September 23	40
5a	May 23	September 20	31
5b	May 14	September 25	8
6a	May 12	October 2	5

Hardiness zones for Montana cities

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


Baker Municipal Airport	4b	−25°F to −20°F	2,971	May 16	Sep 26
Billings Logan Intl Airport	5a	−20°F to −15°F	3,581	May 4	Oct 7
Butte Bert Mooney Airport	5a	−20°F to −15°F	5,506	Jun 13	Sep 5
Drummond Aviation	5b	−15°F to −10°F	4,000	Any month	Any month
Helena Regional Airport	5a	−20°F to −15°F	3,828	May 9	Sep 30
Miles City F Wiley Field	4b	−25°F to −20°F	2,624	May 8	Sep 30
St Marie	4a	−30°F to −25°F	2,756	May 13	Sep 27
St. Mary 1 SSW	4b	−25°F to −20°F	4,555	Jun 3	Sep 8
Superior	6a	−10°F to −5°F	2,710	May 17	Sep 23
Wolf Point 29 ENE	4a	−30°F to −25°F	2,085	May 24	Sep 14

Hardiness zones for 132 towns in Montana

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


Adel	4b	−25°F to −20°F	5,017	Jun 4	Sep 12
Alder 17 S	5a	−20°F to −15°F	5,850	Jun 6	Sep 14
Anaconda	4b	−25°F to −20°F	5,230	Jun 1	Sep 14
Baker Municipal Airport	4b	−25°F to −20°F	2,971	May 16	Sep 26
Biddle 8 SW	4b	−25°F to −20°F	3,631	May 14	Sep 28
Big Sky 2WNW	4b	−25°F to −20°F	6,590	Any month	Any month
Big Timber	5a	−20°F to −15°F	4,100	May 14	Sep 26
Billings Logan Intl Airport	5a	−20°F to −15°F	3,581	May 4	Oct 7
Billings WFO	5a	−20°F to −15°F	3,185	May 5	Oct 3
Blackleaf	4b	−25°F to −20°F	4,235	Jun 9	Sep 3
Boulder	5a	−20°F to −15°F	4,904	Jun 7	Sep 8
Bozeman 6 W Experiment Farm	5a	−20°F to −15°F	4,775	May 23	Sep 23
Bozeman Montana State University	5a	−20°F to −15°F	4,913	May 26	Sep 22
Bridger 2 N	5a	−20°F to −15°F	3,583	May 14	Sep 24
Busby	5a	−20°F to −15°F	3,430	May 23	Sep 15
Butte Bert Mooney Airport	5a	−20°F to −15°F	5,506	Jun 13	Sep 5
Bynum 4 SSE	4b	−25°F to −20°F	4,039	May 16	Sep 27
Carter 14 W	4b	−25°F to −20°F	3,450	May 23	Sep 23
Chester	4a	−30°F to −25°F	3,132	May 24	Sep 17
Chinook	3b	−35°F to −30°F	2,420	May 14	Sep 23
Cohagen	4a	−30°F to −25°F	2,720	May 25	Sep 14
Colstrip	5a	−20°F to −15°F	3,218	May 15	Sep 30
Columbus	5a	−20°F to −15°F	3,602	May 27	Sep 14
Conrad	4a	−30°F to −25°F	3,550	May 20	Sep 19
Cooke City 2 W	4a	−30°F to −25°F	7,483	Any month	Any month
Culbertson	4a	−30°F to −25°F	1,940	May 21	Sep 20
Deer Lodge 3 W	4b	−25°F to −20°F	4,850	Any month	Any month
Divide	5a	−20°F to −15°F	5,350	Jun 10	Sep 7
Drummond Aviation	5b	−15°F to −10°F	4,000	Any month	Any month
Dunkirk 19NNE	4a	−30°F to −25°F	3,323	May 23	Sep 14
Elliston	4b	−25°F to −20°F	5,080	Jun 9	Sep 8
Ennis	5a	−20°F to −15°F	4,953	Jun 16	Sep 4
Eureka Ranger Station	5b	−15°F to −10°F	2,532	May 11	Sep 27
Fairfield	4b	−25°F to −20°F	3,983	May 13	Sep 27
Forsyth	4b	−25°F to −20°F	2,515	May 9	Sep 29
Fort Belknap 2 SW	4a	−30°F to −25°F	2,527	May 16	Sep 22
Fort Benton	4a	−30°F to −25°F	2,649	May 15	Sep 22
Fortine 1 N	5a	−20°F to −15°F	3,000	May 16	Sep 18
Gardiner	4b	−25°F to −20°F	5,275	May 21	Sep 27
Geraldine	4b	−25°F to −20°F	3,145	May 14	Sep 26
Gildford	3b	−35°F to −30°F	2,820	May 24	Sep 15
Glen 4 N	4b	−25°F to −20°F	5,054	Any month	Any month
Glendive	4a	−30°F to −25°F	2,075	May 3	Oct 4
Goldbutte 7 N	4a	−30°F to −25°F	3,498	Any month	Any month
Grass Range	4b	−25°F to −20°F	3,490	May 20	Sep 24
Great Falls 16ST	4b	−25°F to −20°F	3,505	May 6	Oct 1
Hamilton	5b	−15°F to −10°F	3,585	May 21	Sep 22
Harlowton	4b	−25°F to −20°F	4,222	May 23	Sep 16
Haugan 1 W	6a	−10°F to −5°F	3,160	Any month	Any month
Helena Regional Airport	5a	−20°F to −15°F	3,828	May 9	Sep 30
Heron 2 NW	6b	−5°F to 0°F	2,240	May 20	Sep 20
Highwood 7 NE	4b	−25°F to −20°F	3,600	May 7	Oct 2
Hungry Horse Dam	5b	−15°F to −10°F	3,160	May 9	Oct 1
Huntley Experiment Station	4b	−25°F to −20°F	3,034	May 12	Sep 25
Hysham	4b	−25°F to −20°F	2,669	May 10	Sep 29
Hysham 25 SSE	4b	−25°F to −20°F	3,100	May 26	Sep 16
Jackson	5a	−20°F to −15°F	6,480	Any month	Any month
Joliet	5a	−20°F to −15°F	3,838	May 29	Sep 15
Joplin	4a	−30°F to −25°F	3,323	May 21	Sep 19
Jordan	4a	−30°F to −25°F	2,620	May 21	Sep 18
Judith Gap	4b	−25°F to −20°F	4,630	Jun 1	Sep 15
Laurin 2NE	5a	−20°F to −15°F	5,198	May 24	Sep 22
Lewistown	4b	−25°F to −20°F	3,911	May 14	Sep 28
Lindbergh Lake	5a	−20°F to −15°F	4,320	May 20	Sep 22
Livingston 12 S	5a	−20°F to −15°F	5,044	May 19	Sep 25
Logan Landfill	5a	−20°F to −15°F	4,243	May 26	Sep 15
Martinsdale 3 NNW	4b	−25°F to −20°F	4,800	Jun 3	Sep 8
Medicine Lake 3 SE	3b	−35°F to −30°F	1,942	May 16	Sep 18
Melstone	4b	−25°F to −20°F	2,932	May 10	Sep 29
Mildred 5 N	4a	−30°F to −25°F	2,482	May 20	Sep 22
Miles City F Wiley Field	4b	−25°F to −20°F	2,624	May 8	Sep 30
Missoula 2 NE	5b	−15°F to −10°F	3,420	May 10	Oct 1
Missoula 6 NW WFO	5b	−15°F to −10°F	3,197	May 6	Oct 4
Moccasin Experiment Station	4b	−25°F to −20°F	4,300	May 28	Sep 20
Mosby 4 ENE	4b	−25°F to −20°F	2,910	May 5	Oct 4
Mystic Lake	5a	−20°F to −15°F	6,544	Jun 5	Sep 14
Neihart 8 NNW	4b	−25°F to −20°F	5,230	Jun 6	Sep 12
Norris Madison Pwr House	5a	−20°F to −15°F	4,745	Apr 30	Oct 10
Nye #2	5a	−20°F to −15°F	4,840	Jun 1	Sep 11
Olney	5a	−20°F to −15°F	3,165	Any month	Any month
Opheim 12 SSE	3b	−35°F to −30°F	2,936	Jun 5	Sep 2
Ovando 9 SSE	5a	−20°F to −15°F	4,325	Any month	Any month
Plentywood	3b	−35°F to −30°F	2,048	May 25	Sep 14
Plevna	4a	−30°F to −25°F	2,780	May 21	Sep 20
Polebridge	5a	−20°F to −15°F	3,520	Any month	Any month
Polson	6a	−10°F to −5°F	3,010	May 10	Oct 5
Pompeys Pillar 15N	4b	−25°F to −20°F	3,390	May 22	Sep 22
Potomac	5b	−15°F to −10°F	3,690	Any month	Any month
Rapelje	4b	−25°F to −20°F	4,068	May 24	Sep 21
Raymond Border Station	4a	−30°F to −25°F	2,345	May 19	Sep 23
Raynesford 2 NNW	4b	−25°F to −20°F	4,215	May 22	Sep 23
Red Lodge	5a	−20°F to −15°F	5,646	Jun 3	Sep 19
Redstone	3b	−35°F to −30°F	2,106	May 28	Sep 7
Rogers Pass 9 NNE	4b	−25°F to −20°F	4,200	May 21	Sep 15
Roundup	4b	−25°F to −20°F	3,200	May 20	Sep 21
Roy 8 NE	4b	−25°F to −20°F	3,085	May 14	Sep 24
Ryegate	4b	−25°F to −20°F	3,650	May 17	Sep 23
Saco 1 NNW	3b	−35°F to −30°F	2,185	May 15	Sep 23
Saint Ignatius	6a	−10°F to −5°F	2,915	May 12	Oct 2
Saint Regis 1 NE	6a	−10°F to −5°F	2,660	Any month	Any month
Savage	4a	−30°F to −25°F	1,978	May 12	Sep 25
Scobey 4 NW	3b	−35°F to −30°F	2,390	May 28	Sep 6
Seeley Lake Ranger Station	5a	−20°F to −15°F	4,100	Any month	Any month
Shelby	4a	−30°F to −25°F	3,325	May 23	Sep 16
St Marie	4a	−30°F to −25°F	2,756	May 13	Sep 27
St. Mary 1 SSW	4b	−25°F to −20°F	4,555	Jun 3	Sep 8
Stevensville	5b	−15°F to −10°F	3,375	May 22	Sep 19
Sula 14 NE	5a	−20°F to −15°F	5,155	Any month	Any month
Sun River 4 S	4a	−30°F to −25°F	3,600	Jun 2	Sep 10
Sunburst 8 E	4a	−30°F to −25°F	3,700	May 17	Sep 25
Superior	6a	−10°F to −5°F	2,710	May 17	Sep 23
Swan Lake	5b	−15°F to −10°F	3,100	May 17	Sep 19
Thompson Falls Ph	6a	−10°F to −5°F	2,380	May 7	Oct 4
Tizer Gardens	4b	−25°F to −20°F	4,672	Jun 18	Sep 5
Trident	5a	−20°F to −15°F	4,036	May 9	Sep 27
Trout Creek Ranger Station	6a	−10°F to −5°F	2,356	May 20	Sep 21
Twin Bridges	5a	−20°F to −15°F	4,625	Jun 8	Sep 2
Valier	4b	−25°F to −20°F	3,807	May 17	Sep 24
Vida 6 NE	4a	−30°F to −25°F	2,284	May 16	Sep 22
Virginia City	5a	−20°F to −15°F	5,773	Jun 4	Sep 18
W Glacier	5a	−20°F to −15°F	3,148	May 18	Sep 20
Westby	3b	−35°F to −30°F	2,103	May 18	Sep 21
Western Agricultural Rsch Center	5b	−15°F to −10°F	3,608	May 23	Sep 21
Whitefish	5a	−20°F to −15°F	3,100	May 16	Sep 25
Wibaux 2 E	4a	−30°F to −25°F	2,696	May 27	Sep 16
Wilsall 1S	4b	−25°F to −20°F	5,015	Jun 4	Sep 6
Wisdom	5a	−20°F to −15°F	6,060	Any month	Any month
Wolf Point	4a	−30°F to −25°F	2,090	May 8	Sep 28
Wolf Point 29 ENE	4a	−30°F to −25°F	2,085	May 24	Sep 14
Wyola 1 SW	4b	−25°F to −20°F	3,730	May 21	Sep 17
Yellowtail Dam	5a	−20°F to −15°F	3,305	May 7	Oct 5
Zortman	4b	−25°F to −20°F	4,035	May 18	Sep 23

Frequently asked questions

What hardiness zone is Montana?

Montana is in USDA hardiness zones 3b–6b on the 2023 USDA Plant Hardiness Zone Map. Zone 4b is the most common, covering 32% of Montana's ZIP codes, and zone 5a covers 28%. Enter your ZIP code for your exact zone.

What does zone 4b mean?

Zone 4b means the average annual extreme minimum temperature, the coldest night of a typical winter, is −25°F to −20°F (−32°C to −29°C). Perennials, shrubs and trees rated for zone 4b or colder should survive winter there.

What is the coldest hardiness zone in Montana?

Zone 3b is the coldest zone mapped in Montana, found around Opheim 12 SSE, and zone 6b is the warmest, found around Heron 2 NW.

Did Montana'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 4b?

Hardiness zones don't set planting dates; frost dates do. Inside zone 4b in Montana, the median last spring frost varies from May 5 to June 18. 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 Montana 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.