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

Planting zone for 84308 — Cornish, UT

ZIP code 84308 (Cornish, Cache County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 17 and the first fall frost September 18.

Where ZIP 84308 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 17
First frostSep 18
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 Cornish, UT…

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 Cornish, UT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 17median — 50% chance of a later frost
Safe for tender plantsJune 6only 10% chance of frost after
First fall frostSeptember 18median — 10% chance by Sep 1
Growing season121 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 2 and returns around October 1.

From the NOAA station Trenton, UT — 4 miles away, elevation 4,456 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 84308

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 5 – Apr 19
SpinachSow outdoors · Apr 5 – Apr 26
Broccoli, cabbageStart indoors · Mar 8 – Mar 22
Broccoli, cabbageTransplant · Apr 26 – May 10
Onion setsPlant outdoors · Apr 19 – May 3
PotatoesPlant outdoors · Apr 26 – May 10
LettuceSow outdoors · Apr 19 – May 3
Carrots, beetsSow outdoors · Apr 26 – May 10
TomatoesStart indoors · Mar 22 – Apr 5
TomatoesTransplant · May 24 – Jun 7
Peppers, eggplantStart indoors · Mar 8 – Mar 22
Peppers, eggplantTransplant · May 31 – Jun 14
BeansSow outdoors · May 24 – Jun 7
Sweet cornSow outdoors · May 24 – Jun 7
Cucumbers, squashSow outdoors · May 24 – Jun 7
Fall lettuce, spinachSow outdoors · Jul 24 – Aug 7
GarlicPlant cloves · Sep 4 – Oct 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 17) and first fall frost (Sep 18) 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 84308 came on Mar 20 — 17 days earlier than the 1991–2020 average (Apr 6).

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 Utah

546 plants native to the lower 48 states, recorded in Utah, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 30

American beech80 ft · blooms mid spring · low shade tolerance · to −44 °FArizona cypress50 ft · blooms spring · low shade tolerance · to −23 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °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 °F

Shrubs 107

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °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 248

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °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 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 151

alkali 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 °Farctic bluegrass2 ft · high shade tolerance · to −62 °F

Vines 3

trumpet 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 Cornish, UT.

Soil in Cornish, UT

The soil mapped at the center of ZIP 84308 is Trenton — silty clay loam, somewhat poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: TRENTON SILTY CLAY LOAM, MODERATELY DEEP WATER TABLE, 0 TO 2 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 84308; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cornish, UT

Summer high89 °Faverage high, July
Winter low12 °Faverage low, January
Hot days35days a year at 90 °F or more
Freezing nights180nights a year at 32 °F or less
Growing degree days2,082base 50 °F — the season’s usable heat
Longest day15 h 14 mindaylight on June 21
Shortest day9 h 07 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation16.9 inper year, rain and melted snow
Snowfall49 inper year; 73 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 32 °F, low 12 °F 32°12° JanFebruary: average high 37 °F, low 17 °F 37°17° FebMarch: average high 50 °F, low 26 °F 50°26° MarApril: average high 59 °F, low 32 °F 59°32° AprMay: average high 69 °F, low 39 °F 69°39° MayJune: average high 79 °F, low 45 °F 79°45° JunJuly: average high 89 °F, low 51 °F 89°51° JulAugust: average high 88 °F, low 49 °F 88°49° AugSeptember: average high 77 °F, low 40 °F 77°40° SepOctober: average high 63 °F, low 31 °F 63°31° OctNovember: average high 47 °F, low 23 °F 47°23° NovDecember: average high 34 °F, low 14 °F 34°14° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 1.51 in precipitation, 13.6 in snowfall 1.5❄14 JanFebruary: 1.42 in precipitation, 10.4 in snowfall 1.4❄10 FebMarch: 1.70 in precipitation, 4.2 in snowfall 1.7❄4 MarApril: 2.04 in precipitation, 1.9 in snowfall 2.0❄2 AprMay: 2.19 in precipitation, 0.1 in snowfall 2.2 MayJune: 1.20 in precipitation 1.2 JunJuly: 0.56 in precipitation 0.6 JulAugust: 0.83 in precipitation 0.8 AugSeptember: 1.26 in precipitation 1.3 SepOctober: 1.54 in precipitation, 0.4 in snowfall 1.5 OctNovember: 1.25 in precipitation, 4.9 in snowfall 1.3❄5 NovDecember: 1.40 in precipitation, 13.5 in snowfall 1.4❄14 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Trenton, UT (4 mi away); precipitation: Trenton, UT (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

843385b
Trenton, UT · 4 mi
843056a
Clarkston, UT · 5 mi
843206a
Lewiston, UT · 6 mi
843276a
Newton, UT · 7 mi
832866a
Weston, ID · 7 mi
843336a
Richmond, UT · 10 mi
843046a
Cache Junction, UT · 10 mi
832376a
Franklin, ID · 11 mi

Utah planting zones →

Questions about 84308

What planting zone is ZIP code 84308?

ZIP code 84308 (Cornish, UT) 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 Cornish, UT?

The median last spring frost (32 °F) near 84308 is May 17; after June 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Trenton station.

When is the first frost in Cornish, UT?

The median first fall frost near 84308 is September 18, giving a median frost-free growing season of 121 days.

When should I plant tomatoes in 84308?

Start tomato seeds indoors around Mar 22 – Apr 5 and set transplants outside around May 24 – Jun 7, one to three weeks after the median last frost.

How much rain and snow does 84308 get?

About 16.9 inches of precipitation a year and 49 inches of snowfall (NOAA 1991–2020 normals, Trenton station).

How hot do summers get in Cornish, UT?

The average high peaks at 89 °F in July, with about 35 days a year at 90 °F or more.

What kind of soil does 84308 have?

The USDA soil survey maps Trenton at the center of ZIP 84308: silty clay loam, somewhat poorly drained, pH about 7.9 (alkaline).

Did spring come early in Cornish, UT in 2026?

Spring leaf-out near 84308 came on Mar 20 in 2026, 17 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cornish, UT?

Long-day onions: the longest day near 84308 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 84308 change?

Yes. The 2012 USDA map put 84308 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.