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

Planting zone for 80815 — Flagler, CO

ZIP code 80815 (Flagler, Kit Carson County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 5 and the first fall frost October 8.

Where ZIP 80815 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 frostMay 5
First frostOct 8
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Flagler, 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 Flagler, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 5median — 50% chance of a later frost
Safe for tender plantsMay 20only 10% chance of frost after
First fall frostOctober 8median — 10% chance by Sep 27
Growing season155 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 26 and returns around October 16.

From the NOAA station Flagler 1s, CO — 7 miles away, elevation 4,922 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 80815

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 24 – Apr 7
SpinachSow outdoors · Mar 24 – Apr 14
Broccoli, cabbageStart indoors · Feb 24 – Mar 10
Broccoli, cabbageTransplant · Apr 14 – Apr 28
Onion setsPlant outdoors · Apr 7 – Apr 21
PotatoesPlant outdoors · Apr 14 – Apr 28
LettuceSow outdoors · Apr 7 – Apr 21
Carrots, beetsSow outdoors · Apr 14 – Apr 28
TomatoesStart indoors · Mar 10 – Mar 24
TomatoesTransplant · May 12 – May 26
Peppers, eggplantStart indoors · Feb 24 – Mar 10
Peppers, eggplantTransplant · May 19 – Jun 2
BeansSow outdoors · May 12 – May 26
Sweet cornSow outdoors · May 12 – May 26
Cucumbers, squashSow outdoors · May 12 – May 26
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 5) 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 80815 came on Mar 2 — 24 days earlier than the 1991–2020 average (Mar 26).

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.

Trees 27

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 98

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 246

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 163

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 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °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 Flagler, CO.

Soil in Flagler, CO

The soil mapped at the center of ZIP 80815 is Weld — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.6slightly alkaline; 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-Norka silt loams, 0 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 80815; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Flagler, CO

Summer high89 °Faverage high, July
Winter low17 °Faverage low, January
Hot days43days a year at 90 °F or more
Freezing nights167nights a year at 32 °F or less
Growing degree days3,051base 50 °F — the season’s usable heat
Longest day14 h 57 mindaylight on June 21
Shortest day9 h 23 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation16.5 inper year, rain and melted snow
Snowfall25 inper year; 12 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 45 °F, low 17 °F 45°17° JanFebruary: average high 47 °F, low 19 °F 47°19° FebMarch: average high 57 °F, low 27 °F 57°27° MarApril: average high 64 °F, low 35 °F 64°35° AprMay: average high 73 °F, low 44 °F 73°44° MayJune: average high 85 °F, low 54 °F 85°54° JunJuly: average high 89 °F, low 60 °F 89°60° JulAugust: average high 87 °F, low 58 °F 87°58° AugSeptember: average high 79 °F, low 49 °F 79°49° SepOctober: average high 66 °F, low 36 °F 66°36° OctNovember: average high 54 °F, low 26 °F 54°26° NovDecember: average high 44 °F, low 17 °F 44°17° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.34 in precipitation, 5.1 in snowfall 0.3❄5 JanFebruary: 0.31 in precipitation, 3.8 in snowfall 0.3❄4 FebMarch: 0.80 in precipitation, 3.9 in snowfall 0.8❄4 MarApril: 1.37 in precipitation, 3.4 in snowfall 1.4❄3 AprMay: 2.47 in precipitation, 0.6 in snowfall 2.5❄1 MayJune: 2.64 in precipitation 2.6 JunJuly: 3.06 in precipitation 3.1 JulAugust: 2.71 in precipitation 2.7 AugSeptember: 1.24 in precipitation, 0.4 in snowfall 1.2 SepOctober: 0.90 in precipitation, 1 in snowfall 0.9❄1 OctNovember: 0.29 in precipitation, 2.4 in snowfall 0.3❄2 NovDecember: 0.37 in precipitation, 3.9 in snowfall 0.4❄4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Flagler 1s, CO (7 mi away); precipitation: Flagler 1s, CO (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

808045b
Arriba, CO · 8 mi
808345b
Seibert, CO · 13 mi
808616a
Vona, CO · 18 mi
808185b
Genoa, CO · 20 mi
808125b
Cope, CO · 22 mi
808015b
Anton, CO · 24 mi
808366a
Stratton, CO · 28 mi
807405b
Lindon, CO · 29 mi

Colorado planting zones →

Questions about 80815

What planting zone is ZIP code 80815?

ZIP code 80815 (Flagler, 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 Flagler, CO?

The median last spring frost (32 °F) near 80815 is May 5; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Flagler 1s station.

When is the first frost in Flagler, CO?

The median first fall frost near 80815 is October 8, giving a median frost-free growing season of 155 days.

When should I plant tomatoes in 80815?

Start tomato seeds indoors around Mar 10 – Mar 24 and set transplants outside around May 12 – May 26, one to three weeks after the median last frost.

How much rain and snow does 80815 get?

About 16.5 inches of precipitation a year and 25 inches of snowfall (NOAA 1991–2020 normals, Flagler 1s station).

How hot do summers get in Flagler, 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 80815 have?

The USDA soil survey maps Weld at the center of ZIP 80815: silt loam, well drained, pH about 7.6 (slightly alkaline).

Did spring come early in Flagler, CO in 2026?

Spring leaf-out near 80815 came on Mar 2 in 2026, 24 days earlier than the 1991–2020 average (Mar 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Flagler, CO?

Intermediate onions: the longest day near 80815 is 14 h 57 min, so day-neutral types bulb best; long-day varieties may not bulb fully.