Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 80510 — Allenspark, CO

ZIP code 80510 (Allenspark, Boulder County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is June 14 and the first fall frost September 12.

Where ZIP 80510 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 14

First frostSep 12

2012 zone5a

Was 5a on the 2012 map — half a zone 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 Allenspark, 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 Allenspark, CO

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostJune 14median — 50% chance of a later frost

Safe for tender plantsJune 28only 10% chance of frost after

First fall frostSeptember 12median — 10% chance by Aug 25

Growing season92 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 27 and returns around September 25.

From the NOAA station Allenspark 3nw, CO — 5 miles away, elevation 8,501 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 80510

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 3 – May 17

SpinachSow outdoors · May 3 – May 24

Broccoli, cabbageStart indoors · Apr 5 – Apr 19

Broccoli, cabbageTransplant · May 24 – Jun 7

Onion setsPlant outdoors · May 17 – May 31

PotatoesPlant outdoors · May 24 – Jun 7

LettuceSow outdoors · May 17 – May 31

Carrots, beetsSow outdoors · May 24 – Jun 7

TomatoesStart indoors · Apr 19 – May 3

TomatoesTransplant · Jun 21 – Jul 5

Peppers, eggplantStart indoors · Apr 5 – Apr 19

Peppers, eggplantTransplant · Jun 28 – Jul 12

BeansSow outdoors · Jun 21 – Jul 5

Sweet cornSow outdoors · Jun 21 – Jul 5

Cucumbers, squashSow outdoors · Jun 21 – Jul 5

Fall lettuce, spinachSow outdoors · Jul 18 – Aug 1

GarlicPlant cloves · Aug 29 – Oct 3

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 14) and first fall frost (Sep 12) 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 80510 came on Apr 25 — 24 days earlier than the 1991–2020 average (May 19).

average
May 192026
Apr 25

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.

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 Allenspark, CO.

Soil in Allenspark, CO

The soil mapped at the center of ZIP 80510 is Fallriver — moderately decomposed plant material, somewhat excessively drained.

TextureModerately decomposed plant materialtop layer

pH5.6moderately acidic; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter85%high

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Fallriver-Rock outcrop complex, 30 to 70 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 80510; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Allenspark, CO

Summer high74 °Faverage high, July

Winter low14 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights225nights a year at 32 °F or less

Growing degree days831base 50 °F — the season’s usable heat

Longest day15 h 02 mindaylight on June 21

Shortest day9 h 18 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation31.3 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Allenspark 3nw, CO (5 mi away); precipitation: Wild Basin, CO (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

Grand Lake, CO · 13 mi

805175a

Estes Park, CO · 13 mi

804555b

Jamestown, CO · 14 mi

Colorado planting zones →

Questions about 80510

What planting zone is ZIP code 80510?

ZIP code 80510 (Allenspark, 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 Allenspark, CO?

The median last spring frost (32 °F) near 80510 is June 14; after June 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Allenspark 3nw station.

When is the first frost in Allenspark, CO?

The median first fall frost near 80510 is September 12, giving a median frost-free growing season of 92 days.

When should I plant tomatoes in 80510?

Start tomato seeds indoors around Apr 19 – May 3 and set transplants outside around Jun 21 – Jul 5, one to three weeks after the median last frost.

How much rain and snow does 80510 get?

About 31.3 inches of precipitation a year (NOAA 1991–2020 normals, Wild Basin station).

How hot do summers get in Allenspark, CO?

The average high peaks at 74 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 80510 have?

The USDA soil survey maps Fallriver at the center of ZIP 80510: moderately decomposed plant material, somewhat excessively drained, pH about 5.6 (moderately acidic).

Did spring come early in Allenspark, CO in 2026?

Spring leaf-out near 80510 came on Apr 25 in 2026, 24 days earlier than the 1991–2020 average (May 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Allenspark, CO?

Long-day onions: the longest day near 80510 is 15 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 80510 change?

Yes. The 2012 USDA map put 80510 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.