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

Planting zone for 80045 — Aurora, CO

ZIP code 80045 (Aurora, Adams 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 8.

Where ZIP 80045 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 8

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 Aurora, 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 Aurora, 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 16only 10% chance of frost after

First fall frostOctober 8median — 10% chance by Sep 25

Growing season156 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 22 and returns around October 18.

From the NOAA station Denver-Stapleton, CO — 2 miles away, elevation 5,286 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 80045

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 13 – Aug 27

GarlicPlant cloves · Sep 24 – Oct 29

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 4) and first fall frost (Oct 8) 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 80045 came on Feb 19 — 28 days earlier than the 1991–2020 average (Mar 19).

average
Mar 192026
Feb 19

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).

Soil in Aurora, CO

The soil mapped at the center of ZIP 80045 is Weld — loam, well drained.

TextureLoama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Weld 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 80045; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Aurora, CO

Summer high90 °Faverage high, July

Winter low18 °Faverage low, January

Hot days42days a year at 90 °F or more

Freezing nights156nights a year at 32 °F or less

Growing degree days3,011base 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

Precipitation16.3 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: Denver-Stapleton, CO (2 mi away); precipitation: Aurora 4.2 Nnw, CO (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

All 17 ZIP codes in Aurora → · Colorado planting zones →

Questions about 80045

What planting zone is ZIP code 80045?

ZIP code 80045 (Aurora, 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 Aurora, CO?

The median last spring frost (32 °F) near 80045 is May 4; after May 16 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Denver-Stapleton station.

When is the first frost in Aurora, CO?

The median first fall frost near 80045 is October 8, giving a median frost-free growing season of 156 days.

When should I plant tomatoes in 80045?

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 80045 get?

About 16.3 inches of precipitation a year (NOAA 1991–2020 normals, Aurora 4.2 Nnw station).

How hot do summers get in Aurora, CO?

The average high peaks at 90 °F in July, with about 42 days a year at 90 °F or more.

What kind of soil does 80045 have?

The USDA soil survey maps Weld at the center of ZIP 80045: loam, well drained, pH about 7.0 (neutral).

Did spring come early in Aurora, CO in 2026?

Spring leaf-out near 80045 came on Feb 19 in 2026, 28 days earlier than the 1991–2020 average (Mar 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Aurora, CO?

Intermediate onions: the longest day near 80045 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.