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

Planting zone for 81240 — Penrose, CO

ZIP code 81240 (Penrose, Fremont County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 4 and the first fall frost October 7.

Where ZIP 81240 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostMay 4
First frostOct 7
2012 zone6a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Penrose, 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 Penrose, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 4median — 50% chance of a later frost
Safe for tender plantsMay 18only 10% chance of frost after
First fall frostOctober 7median — 10% chance by Sep 25
Growing season153 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 26 and returns around October 17.

From the NOAA station Canon City, CO — 11 miles away, elevation 5,378 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 81240

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 23 – Apr 6
SpinachSow outdoors · Mar 23 – Apr 13
Broccoli, cabbageStart indoors · Feb 23 – Mar 9
Broccoli, cabbageTransplant · Apr 13 – Apr 27
Onion setsPlant outdoors · Apr 6 – Apr 20
PotatoesPlant outdoors · Apr 13 – Apr 27
LettuceSow outdoors · Apr 6 – Apr 20
Carrots, beetsSow outdoors · Apr 13 – Apr 27
TomatoesStart indoors · Mar 9 – Mar 23
TomatoesTransplant · May 11 – May 25
Peppers, eggplantStart indoors · Feb 23 – Mar 9
Peppers, eggplantTransplant · May 18 – Jun 1
BeansSow outdoors · May 11 – May 25
Sweet cornSow outdoors · May 11 – May 25
Cucumbers, squashSow outdoors · May 11 – May 25
Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26
GarlicPlant cloves · Sep 23 – Oct 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 4) and first fall frost (Oct 7) 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 81240 came on Feb 20 — 28 days earlier than the 1991–2020 average (Mar 20).

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 6a in Colorado

563 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 28

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 104

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 251

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 167

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 4

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Penrose, CO.

Soil in Penrose, CO

The soil mapped at the center of ZIP 81240 is Travessilla — channery sandy loam, well drained.

TextureChannery sandy loamdrains and warms fast; dries out and needs more feeding
pH7.0neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Travessilla-Rock outcrop complex, 5 to 50 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 81240; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Penrose, CO

Summer high89 °Faverage high, July
Winter low18 °Faverage low, January
Hot days43days a year at 90 °F or more
Freezing nights144nights a year at 32 °F or less
Growing degree days3,011base 50 °F — the season’s usable heat
Longest day14 h 51 mindaylight on June 21
Shortest day9 h 28 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation15.2 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 49 °F, low 18 °F 49°18° JanFebruary: average high 50 °F, low 20 °F 50°20° FebMarch: average high 59 °F, low 26 °F 59°26° MarApril: average high 64 °F, low 33 °F 64°33° AprMay: average high 73 °F, low 43 °F 73°43° MayJune: average high 85 °F, low 52 °F 85°52° JunJuly: average high 89 °F, low 59 °F 89°59° JulAugust: average high 87 °F, low 57 °F 87°57° AugSeptember: average high 80 °F, low 48 °F 80°48° SepOctober: average high 69 °F, low 36 °F 69°36° OctNovember: average high 57 °F, low 26 °F 57°26° NovDecember: average high 49 °F, low 19 °F 49°19° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.52 in precipitation 0.5 JanFebruary: 0.61 in precipitation 0.6 FebMarch: 1.03 in precipitation 1.0 MarApril: 1.71 in precipitation 1.7 AprMay: 1.77 in precipitation 1.8 MayJune: 1.15 in precipitation 1.1 JunJuly: 3.05 in precipitation 3.0 JulAugust: 2.39 in precipitation 2.4 AugSeptember: 1.02 in precipitation 1.0 SepOctober: 0.83 in precipitation 0.8 OctNovember: 0.58 in precipitation 0.6 NovDecember: 0.57 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Canon City, CO (11 mi away); precipitation: Penrose 2.3 Nnw, CO (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

812906a
Florence, CO · 9 mi
812216a
Coal Creek, CO · 11 mi
812266a
Florence, CO · 12 mi
809266a
Colorado Springs, CO · 12 mi
812446a
Rockvale, CO · 12 mi
808605b
Victor, CO · 14 mi
810076a
Pueblo, CO · 15 mi
809026a
Colorado Springs, CO · 17 mi

Colorado planting zones →

Questions about 81240

What planting zone is ZIP code 81240?

ZIP code 81240 (Penrose, CO) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Penrose, CO?

The median last spring frost (32 °F) near 81240 is May 4; after May 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Canon City station.

When is the first frost in Penrose, CO?

The median first fall frost near 81240 is October 7, giving a median frost-free growing season of 153 days.

When should I plant tomatoes in 81240?

Start tomato seeds indoors around Mar 9 – Mar 23 and set transplants outside around May 11 – May 25, one to three weeks after the median last frost.

How much rain and snow does 81240 get?

About 15.2 inches of precipitation a year (NOAA 1991–2020 normals, Penrose 2.3 Nnw station).

How hot do summers get in Penrose, CO?

The average high peaks at 89 °F in July, with about 43 days a year at 90 °F or more.

What kind of soil does 81240 have?

The USDA soil survey maps Travessilla at the center of ZIP 81240: channery sandy loam, well drained, pH about 7.0 (neutral).

Did spring come early in Penrose, CO in 2026?

Spring leaf-out near 81240 came on Feb 20 in 2026, 28 days earlier than the 1991–2020 average (Mar 20), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Penrose, CO?

Intermediate onions: the longest day near 81240 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.