Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 30, 2026

Planting zone for 81154 — South Fork, CO

ZIP code 81154 (South Fork, Rio Grande County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 23 and the first fall frost September 25.

Where ZIP 81154 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 23

First frostSep 25

2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for South Fork, 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 South Fork, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 23median — 50% chance of a later frost

Safe for tender plantsJune 8only 10% chance of frost after

First fall frostSeptember 25median — 10% chance by Sep 13

Growing season123 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 9 and returns around October 4.

From the NOAA station Del Norte 3ene, CO — 20 miles away, elevation 7,845 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 81154

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 11 – Apr 25

SpinachSow outdoors · Apr 11 – May 2

Broccoli, cabbageStart indoors · Mar 14 – Mar 28

Broccoli, cabbageTransplant · May 2 – May 16

Onion setsPlant outdoors · Apr 25 – May 9

PotatoesPlant outdoors · May 2 – May 16

LettuceSow outdoors · Apr 25 – May 9

Carrots, beetsSow outdoors · May 2 – May 16

TomatoesStart indoors · Mar 28 – Apr 11

TomatoesTransplant · May 30 – Jun 13

Peppers, eggplantStart indoors · Mar 14 – Mar 28

Peppers, eggplantTransplant · Jun 6 – Jun 20

BeansSow outdoors · May 30 – Jun 13

Sweet cornSow outdoors · May 30 – Jun 13

Cucumbers, squashSow outdoors · May 30 – Jun 13

Fall lettuce, spinachSow outdoors · Jul 31 – Aug 14

GarlicPlant cloves · Sep 11 – Oct 16

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 23) and first fall frost (Sep 25) 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 81154 came on Mar 26 — 37 days earlier than the 1991–2020 average (May 2).

average
May 22026
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.

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 South Fork, CO.

Soil in South Fork, CO

The soil mapped at the center of ZIP 81154 is Cabin — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Cabin-Silas association, 0 to 15 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 81154; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in South Fork, CO

Summer high79 °Faverage high, July

Winter low−10 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights273nights a year at 32 °F or less

Growing degree days756base 50 °F — the season’s usable heat

Longest day14 h 46 mindaylight on June 21

Shortest day9 h 33 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation17.4 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: Creede Wtp, CO (20 mi away); precipitation: South Fork 0.6 S, CO (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

811325b

Del Norte, CO · 15 mi

811305a

Creede, CO · 24 mi

811445a

Monte Vista, CO · 29 mi

811575b

Pagosa Springs, CO · 31 mi

811354b

Homelake, CO · 32 mi

811475b

Pagosa Springs, CO · 33 mi

Colorado planting zones →

Questions about 81154

What planting zone is ZIP code 81154?

ZIP code 81154 (South Fork, 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 South Fork, CO?

The median last spring frost (32 °F) near 81154 is May 23; after June 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Del Norte 3ene station.

When is the first frost in South Fork, CO?

The median first fall frost near 81154 is September 25, giving a median frost-free growing season of 123 days.

When should I plant tomatoes in 81154?

Start tomato seeds indoors around Mar 28 – Apr 11 and set transplants outside around May 30 – Jun 13, one to three weeks after the median last frost.

How much rain and snow does 81154 get?

About 17.4 inches of precipitation a year (NOAA 1991–2020 normals, South Fork 0.6 S station).

How hot do summers get in South Fork, CO?

The average high peaks at 79 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 81154 have?

The USDA soil survey maps Cabin at the center of ZIP 81154: fine sandy loam, well drained, pH about 7.0 (neutral).

Did spring come early in South Fork, CO in 2026?

Spring leaf-out near 81154 came on Mar 26 in 2026, 37 days earlier than the 1991–2020 average (May 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in South Fork, CO?

Intermediate onions: the longest day near 81154 is 14 h 46 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 81154 change?

Yes. The 2012 USDA map put 81154 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.