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

Planting zone for 81640 — Maybell, CO

ZIP code 81640 (Maybell, Moffat County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is June 16 and the first fall frost September 9.

Where ZIP 81640 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 frostJun 16

First frostSep 9

2012 zone4b

Was 4b on the 2012 map — 1.5 zones 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 Maybell, 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 Maybell, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 16median — 50% chance of a later frost

Safe for tender plantsJuly 1only 10% chance of frost after

First fall frostSeptember 9median — 10% chance by Aug 26

Growing season83 daysfrost-free, median

A hard freeze (28 °F) usually ends around June 1 and returns around September 19.

From the NOAA station Maybell, CO — 24 miles away, elevation 5,945 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 81640

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 5 – May 19

SpinachSow outdoors · May 5 – May 26

Broccoli, cabbageStart indoors · Apr 7 – Apr 21

Broccoli, cabbageTransplant · May 26 – Jun 9

Onion setsPlant outdoors · May 19 – Jun 2

PotatoesPlant outdoors · May 26 – Jun 9

LettuceSow outdoors · May 19 – Jun 2

Carrots, beetsSow outdoors · May 26 – Jun 9

TomatoesStart indoors · Apr 21 – May 5

TomatoesTransplant · Jun 23 – Jul 7

Peppers, eggplantStart indoors · Apr 7 – Apr 21

Peppers, eggplantTransplant · Jun 30 – Jul 14

BeansSow outdoors · Jun 23 – Jul 7

Sweet cornSow outdoors · Jun 23 – Jul 7

Cucumbers, squashSow outdoors · Jun 23 – Jul 7

Fall lettuce, spinachSow outdoors · Jul 15 – Jul 29

GarlicPlant cloves · Aug 26 – Sep 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 16) and first fall frost (Sep 9) 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 81640 came on Mar 20 — 27 days earlier than the 1991–2020 average (Apr 16).

average
Apr 162026
Mar 20

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.

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 Maybell, CO.

Soil in Maybell, CO

The soil mapped at the center of ZIP 81640 is Grieves — loamy fine sand, somewhat excessively drained.

TextureLoamy fine sanddrains and warms fast; dries out and needs more feeding

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Grieves-Crestman complex, 10 to 40 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 81640; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Maybell, CO

Summer high86 °Faverage high, July

Winter low1 °Faverage low, January

Hot days21days a year at 90 °F or more

Freezing nights227nights a year at 32 °F or less

Growing degree days1,564base 50 °F — the season’s usable heat

Longest day15 h 05 mindaylight on June 21

Shortest day9 h 15 mindaylight on December 21

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

Precipitation12.6 inper year, rain and melted snow

Snowfall55 inper year; 98 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Maybell, CO (24 mi away); precipitation: Maybell, CO (24 mi away). 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.

Dutch John, UT · 40 mi

Rock Springs, WY · 55 mi

Colorado planting zones →

Questions about 81640

What planting zone is ZIP code 81640?

ZIP code 81640 (Maybell, 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 Maybell, CO?

The median last spring frost (32 °F) near 81640 is June 16; after July 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Maybell station.

When is the first frost in Maybell, CO?

The median first fall frost near 81640 is September 9, giving a median frost-free growing season of 83 days.

When should I plant tomatoes in 81640?

Start tomato seeds indoors around Apr 21 – May 5 and set transplants outside around Jun 23 – Jul 7, one to three weeks after the median last frost.

How much rain and snow does 81640 get?

About 12.6 inches of precipitation a year and 55 inches of snowfall (NOAA 1991–2020 normals, Maybell station).

How hot do summers get in Maybell, CO?

The average high peaks at 86 °F in July, with about 21 days a year at 90 °F or more.

What kind of soil does 81640 have?

The USDA soil survey maps Grieves at the center of ZIP 81640: loamy fine sand, somewhat excessively drained, pH about 7.9 (alkaline).

Did spring come early in Maybell, CO in 2026?

Spring leaf-out near 81640 came on Mar 20 in 2026, 27 days earlier than the 1991–2020 average (Apr 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Maybell, CO?

Long-day onions: the longest day near 81640 is 15 h 05 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 81640 change?

Yes. The 2012 USDA map put 81640 in zone 4b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.