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

Planting zone for 80161 — Littleton, CO

ZIP code 80161 (Littleton, Arapahoe County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 2 and the first fall frost October 11.

Where ZIP 80161 is

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 2
First frostOct 11
2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Littleton, 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 Littleton, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 2median — 50% chance of a later frost
Safe for tender plantsMay 17only 10% chance of frost after
First fall frostOctober 11median — 10% chance by Sep 27
Growing season160 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 21.

From the NOAA station Marston Fltr Plt, CO — 2 miles away, elevation 5,611 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 80161

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 21 – Apr 4
SpinachSow outdoors · Mar 21 – Apr 11
Broccoli, cabbageStart indoors · Feb 21 – Mar 7
Broccoli, cabbageTransplant · Apr 11 – Apr 25
Onion setsPlant outdoors · Apr 4 – Apr 18
PotatoesPlant outdoors · Apr 11 – Apr 25
LettuceSow outdoors · Apr 4 – Apr 18
Carrots, beetsSow outdoors · Apr 11 – Apr 25
TomatoesStart indoors · Mar 7 – Mar 21
TomatoesTransplant · May 9 – May 23
Peppers, eggplantStart indoors · Feb 21 – Mar 7
Peppers, eggplantTransplant · May 16 – May 30
BeansSow outdoors · May 9 – May 23
Sweet cornSow outdoors · May 9 – May 23
Cucumbers, squashSow outdoors · May 9 – May 23
Fall lettuce, spinachSow outdoors · Aug 16 – Aug 30
GarlicPlant cloves · Sep 27 – Nov 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 2) and first fall frost (Oct 11) 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 80161 came on Feb 20 — 26 days earlier than the 1991–2020 average (Mar 18).

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 Littleton, CO.

Soil in Littleton, CO

The soil mapped at the center of ZIP 80161 is Nunn — loam, well drained.

TextureLoama good balance for most vegetables
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Nunn loam, 1 to 3 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 80161; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Littleton, CO

Summer high86 °Faverage high, July
Winter low19 °Faverage low, January
Hot days33days a year at 90 °F or more
Freezing nights147nights a year at 32 °F or less
Growing degree days2,772base 50 °F — the season’s usable heat
Longest day14 h 58 mindaylight on June 21
Shortest day9 h 22 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation18.7 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 46 °F, low 19 °F 46°19° JanFebruary: average high 47 °F, low 20 °F 47°20° FebMarch: average high 55 °F, low 28 °F 55°28° MarApril: average high 60 °F, low 35 °F 60°35° AprMay: average high 69 °F, low 44 °F 69°44° MayJune: average high 81 °F, low 53 °F 81°53° JunJuly: average high 86 °F, low 60 °F 86°60° JulAugust: average high 85 °F, low 58 °F 85°58° AugSeptember: average high 77 °F, low 49 °F 77°49° SepOctober: average high 64 °F, low 37 °F 64°37° OctNovember: average high 53 °F, low 28 °F 53°28° NovDecember: average high 45 °F, low 20 °F 45°20° Dec

Precipitation by month inches

0″1″2″3″January: 0.61 in precipitation 0.6 JanFebruary: 0.78 in precipitation 0.8 FebMarch: 1.64 in precipitation 1.6 MarApril: 2.48 in precipitation 2.5 AprMay: 2.56 in precipitation 2.6 MayJune: 1.77 in precipitation 1.8 JunJuly: 2.33 in precipitation 2.3 JulAugust: 2.04 in precipitation 2.0 AugSeptember: 1.51 in precipitation 1.5 SepOctober: 1.52 in precipitation 1.5 OctNovember: 0.88 in precipitation 0.9 NovDecember: 0.56 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Marston Fltr Plt, CO (2 mi away); precipitation: Denver 9.4 S, CO (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

801606a
Littleton, CO · <1 mi
801656a
Littleton, CO · <1 mi
801666a
Littleton, CO · <1 mi
801206a
Littleton, CO · 1 mi
801106a
Englewood, CO · 2 mi
801236a
Littleton, CO · 3 mi
801506a
Englewood, CO · 3 mi
801516a
Englewood, CO · 3 mi

All 16 ZIP codes in Littleton → · Colorado planting zones →

Questions about 80161

What planting zone is ZIP code 80161?

ZIP code 80161 (Littleton, 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 Littleton, CO?

The median last spring frost (32 °F) near 80161 is May 2; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Marston Fltr Plt station.

When is the first frost in Littleton, CO?

The median first fall frost near 80161 is October 11, giving a median frost-free growing season of 160 days.

When should I plant tomatoes in 80161?

Start tomato seeds indoors around Mar 7 – Mar 21 and set transplants outside around May 9 – May 23, one to three weeks after the median last frost.

How much rain and snow does 80161 get?

About 18.7 inches of precipitation a year (NOAA 1991–2020 normals, Denver 9.4 S station).

How hot do summers get in Littleton, CO?

The average high peaks at 86 °F in July, with about 33 days a year at 90 °F or more.

What kind of soil does 80161 have?

The USDA soil survey maps Nunn at the center of ZIP 80161: loam, well drained, pH about 7.2 (neutral).

Did spring come early in Littleton, CO in 2026?

Spring leaf-out near 80161 came on Feb 20 in 2026, 26 days earlier than the 1991–2020 average (Mar 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Littleton, CO?

Intermediate onions: the longest day near 80161 is 14 h 58 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 80161 change?

Yes. The 2012 USDA map put 80161 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.