Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 80451 — Hot Sulphur Springs, CO

ZIP code 80451 (Hot Sulphur Springs, Grand County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is June 12 and the first fall frost September 10.

Where ZIP 80451 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostJun 12
First frostSep 10
2012 zone4a

Was 4a on the 2012 map — 1.5 zones warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Hot Sulphur Springs, CO…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Hot Sulphur Springs, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 12median — 50% chance of a later frost
Safe for tender plantsJune 25only 10% chance of frost after
First fall frostSeptember 10median — 10% chance by Aug 31
Growing season89 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 26 and returns around September 20.

From the NOAA station Williams Fork Dam, CO — 9 miles away, elevation 7,618 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 80451

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · May 1 – May 15
SpinachSow outdoors · May 1 – May 22
Broccoli, cabbageStart indoors · Apr 3 – Apr 17
Broccoli, cabbageTransplant · May 22 – Jun 5
Onion setsPlant outdoors · May 15 – May 29
PotatoesPlant outdoors · May 22 – Jun 5
LettuceSow outdoors · May 15 – May 29
Carrots, beetsSow outdoors · May 22 – Jun 5
TomatoesStart indoors · Apr 17 – May 1
TomatoesTransplant · Jun 19 – Jul 3
Peppers, eggplantStart indoors · Apr 3 – Apr 17
Peppers, eggplantTransplant · Jun 26 – Jul 10
BeansSow outdoors · Jun 19 – Jul 3
Sweet cornSow outdoors · Jun 19 – Jul 3
Cucumbers, squashSow outdoors · Jun 19 – Jul 3
Fall lettuce, spinachSow outdoors · Jul 16 – Jul 30
GarlicPlant cloves · Aug 27 – Oct 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 12) and first fall frost (Sep 10) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 80451 came on Apr 25 — 15 days earlier than the 1991–2020 average (May 10).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 5b in Colorado

546 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 27

American elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack walnut100 ft · blooms late spring · high shade tolerance · to −28 °Fblack willow100 ft · blooms early spring · high shade tolerance · to −58 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °F

Shrubs 98

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FApache plume6 ft · blooms late spring · high shade tolerance · to −23 °F

Wildflowers & perennials 246

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine aster0.3 ft · blooms early summer · medium shade tolerance · to −28 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °F

Grasses 163

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Hot Sulphur Springs, CO.

Soil in Hot Sulphur Springs, CO

The soil mapped at the center of ZIP 80451 is Frisco family — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH5.6moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter85%high
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Frisco, sandstone substratum-Howlett, moist-Scout, moist families complex, 5 to 40 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 80451; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hot Sulphur Springs, CO

Summer high79 °Faverage high, July
Winter low0 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights242nights a year at 32 °F or less
Growing degree days1,036base 50 °F — the season’s usable heat
Longest day15 h 01 mindaylight on June 21
Shortest day9 h 19 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation14.3 inper year, rain and melted snow
Snowfall81 inper year; 144 days with snow on the ground

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 26 °F, low 0 °F 26°0° JanFebruary: average high 31 °F, low 4 °F 31°4° FebMarch: average high 42 °F, low 15 °F 42°15° MarApril: average high 52 °F, low 24 °F 52°24° AprMay: average high 62 °F, low 32 °F 62°32° MayJune: average high 73 °F, low 38 °F 73°38° JunJuly: average high 79 °F, low 45 °F 79°45° JulAugust: average high 77 °F, low 43 °F 77°43° AugSeptember: average high 70 °F, low 35 °F 70°35° SepOctober: average high 57 °F, low 25 °F 57°25° OctNovember: average high 41 °F, low 15 °F 41°15° NovDecember: average high 28 °F, low 4 °F 28°4° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″January: 1.00 in precipitation, 14.2 in snowfall 1.0❄14 JanFebruary: 0.95 in precipitation, 13.6 in snowfall 0.9❄14 FebMarch: 0.98 in precipitation, 10.4 in snowfall 1.0❄10 MarApril: 1.46 in precipitation, 11.9 in snowfall 1.5❄12 AprMay: 1.53 in precipitation, 2.7 in snowfall 1.5❄3 MayJune: 0.99 in precipitation, 0.1 in snowfall 1.0 JunJuly: 1.44 in precipitation 1.4 JulAugust: 1.44 in precipitation 1.4 AugSeptember: 1.40 in precipitation, 0.3 in snowfall 1.4 SepOctober: 1.26 in precipitation, 4.8 in snowfall 1.3❄5 OctNovember: 0.92 in precipitation, 9.9 in snowfall 0.9❄10 NovDecember: 0.88 in precipitation, 13.3 in snowfall 0.9❄13 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Williams Fork Dam, CO (9 mi away); precipitation: Williams Fork Dam, CO (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

6 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

804685a
Parshall, CO · 9 mi
804785b
Tabernash, CO · 10 mi
804465a
Granby, CO · 10 mi
804425b
Fraser, CO · 11 mi
804825a
Winter Park, CO · 17 mi
804595a
Kremmling, CO · 21 mi
804475a
Grand Lake, CO · 21 mi
804985a
Silverthorne, CO · 24 mi

Colorado planting zones →

Questions about 80451

What planting zone is ZIP code 80451?

ZIP code 80451 (Hot Sulphur Springs, CO) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Hot Sulphur Springs, CO?

The median last spring frost (32 °F) near 80451 is June 12; after June 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Williams Fork Dam station.

When is the first frost in Hot Sulphur Springs, CO?

The median first fall frost near 80451 is September 10, giving a median frost-free growing season of 89 days.

When should I plant tomatoes in 80451?

Start tomato seeds indoors around Apr 17 – May 1 and set transplants outside around Jun 19 – Jul 3, one to three weeks after the median last frost.

How much rain and snow does 80451 get?

About 14.3 inches of precipitation a year and 81 inches of snowfall (NOAA 1991–2020 normals, Williams Fork Dam station).

How hot do summers get in Hot Sulphur Springs, CO?

The average high peaks at 79 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 80451 have?

The USDA soil survey maps Frisco family at the center of ZIP 80451: slightly decomposed plant material, well drained, pH about 5.6 (moderately acidic).

Did spring come early in Hot Sulphur Springs, CO in 2026?

Spring leaf-out near 80451 came on Apr 25 in 2026, 15 days earlier than the 1991–2020 average (May 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hot Sulphur Springs, CO?

Long-day onions: the longest day near 80451 is 15 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 80451 change?

Yes. The 2012 USDA map put 80451 in zone 4a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.