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

Planting zone for 80402 — Golden, CO

ZIP code 80402 (Golden, Jefferson County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 3 and the first fall frost October 14.

Where ZIP 80402 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 3
First frostOct 14
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 Golden, 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 Golden, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 3median — 50% chance of a later frost
Safe for tender plantsMay 17only 10% chance of frost after
First fall frostOctober 14median — 10% chance by Sep 30
Growing season161 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 25 and returns around October 23.

From the NOAA station Ralston Rsvr, CO — 5 miles away, elevation 5,899 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 80402

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 22 – Apr 5
SpinachSow outdoors · Mar 22 – Apr 12
Broccoli, cabbageStart indoors · Feb 22 – Mar 8
Broccoli, cabbageTransplant · Apr 12 – Apr 26
Onion setsPlant outdoors · Apr 5 – Apr 19
PotatoesPlant outdoors · Apr 12 – Apr 26
LettuceSow outdoors · Apr 5 – Apr 19
Carrots, beetsSow outdoors · Apr 12 – Apr 26
TomatoesStart indoors · Mar 8 – Mar 22
TomatoesTransplant · May 10 – May 24
Peppers, eggplantStart indoors · Feb 22 – Mar 8
Peppers, eggplantTransplant · May 17 – May 31
BeansSow outdoors · May 10 – May 24
Sweet cornSow outdoors · May 10 – May 24
Cucumbers, squashSow outdoors · May 10 – May 24
Fall lettuce, spinachSow outdoors · Aug 19 – Sep 2
GarlicPlant cloves · Sep 30 – Nov 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 14) 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 80402 came on Feb 19 — 32 days earlier than the 1991–2020 average (Mar 23).

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 Golden, CO.

Soil in Golden, CO

The soil mapped at the center of ZIP 80402 is Denver — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Denver-Urban land complex, 2 to 5 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 80402; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Golden, CO

Summer high87 °Faverage high, July
Winter low22 °Faverage low, February
Hot days28days a year at 90 °F or more
Freezing nights133nights a year at 32 °F or less
Growing degree days2,937base 50 °F — the season’s usable heat
Longest day14 h 59 mindaylight on June 21
Shortest day9 h 21 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation20.8 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 45 °F, low 23 °F 45°23° JanFebruary: average high 46 °F, low 22 °F 46°22° FebMarch: average high 54 °F, low 29 °F 54°29° MarApril: average high 60 °F, low 35 °F 60°35° AprMay: average high 69 °F, low 45 °F 69°45° MayJune: average high 81 °F, low 55 °F 81°55° JunJuly: average high 87 °F, low 61 °F 87°61° JulAugust: average high 84 °F, low 59 °F 84°59° AugSeptember: average high 76 °F, low 51 °F 76°51° SepOctober: average high 64 °F, low 39 °F 64°39° OctNovember: average high 53 °F, low 30 °F 53°30° NovDecember: average high 45 °F, low 23 °F 45°23° Dec

Precipitation by month inches

0″1″2″3″January: 0.73 in precipitation 0.7 JanFebruary: 0.93 in precipitation 0.9 FebMarch: 1.79 in precipitation 1.8 MarApril: 2.95 in precipitation 3.0 AprMay: 2.84 in precipitation 2.8 MayJune: 2.38 in precipitation 2.4 JunJuly: 2.10 in precipitation 2.1 JulAugust: 2.13 in precipitation 2.1 AugSeptember: 1.54 in precipitation 1.5 SepOctober: 1.46 in precipitation 1.5 OctNovember: 1.03 in precipitation 1.0 NovDecember: 0.87 in precipitation 0.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Ralston Rsvr, CO (5 mi away); precipitation: Golden 1.2 Nw, CO (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

804015b
Golden, CO · 3 mi
802286a
Denver, CO · 5 mi
802156a
Denver, CO · 6 mi
800336a
Wheat Ridge, CO · 6 mi
804535b
Idledale, CO · 6 mi
800026a
Arvada, CO · 7 mi
800046a
Arvada, CO · 7 mi
804035b
Golden, CO · 7 mi

All 3 ZIP codes in Golden → · Colorado planting zones →

Questions about 80402

What planting zone is ZIP code 80402?

ZIP code 80402 (Golden, 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 Golden, CO?

The median last spring frost (32 °F) near 80402 is May 3; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ralston Rsvr station.

When is the first frost in Golden, CO?

The median first fall frost near 80402 is October 14, giving a median frost-free growing season of 161 days.

When should I plant tomatoes in 80402?

Start tomato seeds indoors around Mar 8 – Mar 22 and set transplants outside around May 10 – May 24, one to three weeks after the median last frost.

How much rain and snow does 80402 get?

About 20.8 inches of precipitation a year (NOAA 1991–2020 normals, Golden 1.2 Nw station).

How hot do summers get in Golden, CO?

The average high peaks at 87 °F in July, with about 28 days a year at 90 °F or more.

What kind of soil does 80402 have?

The USDA soil survey maps Denver at the center of ZIP 80402: clay loam, well drained, pH about 7.2 (neutral).

Did spring come early in Golden, CO in 2026?

Spring leaf-out near 80402 came on Feb 19 in 2026, 32 days earlier than the 1991–2020 average (Mar 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Golden, CO?

Intermediate onions: the longest day near 80402 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 80402 change?

Yes. The 2012 USDA map put 80402 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.