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

Planting zone for 84309 — Deweyville, UT

ZIP code 84309 (Deweyville, Box Elder County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 24 and the first fall frost October 17.

Where ZIP 84309 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostApr 24

First frostOct 17

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Deweyville, 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 Deweyville, UT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 24median — 50% chance of a later frost

Safe for tender plantsMay 9only 10% chance of frost after

First fall frostOctober 17median — 10% chance by Oct 3

Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around October 26.

From the NOAA station Tremonton, UT — 3 miles away, elevation 4,311 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 84309

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 13 – Mar 27

SpinachSow outdoors · Mar 13 – Apr 3

Broccoli, cabbageStart indoors · Feb 13 – Feb 27

Broccoli, cabbageTransplant · Apr 3 – Apr 17

Onion setsPlant outdoors · Mar 27 – Apr 10

PotatoesPlant outdoors · Apr 3 – Apr 17

LettuceSow outdoors · Mar 27 – Apr 10

Carrots, beetsSow outdoors · Apr 3 – Apr 17

TomatoesStart indoors · Feb 27 – Mar 13

TomatoesTransplant · May 1 – May 15

Peppers, eggplantStart indoors · Feb 13 – Feb 27

Peppers, eggplantTransplant · May 8 – May 22

BeansSow outdoors · May 1 – May 15

Sweet cornSow outdoors · May 1 – May 15

Cucumbers, squashSow outdoors · May 1 – May 15

Fall lettuce, spinachSow outdoors · Aug 22 – Sep 5

GarlicPlant cloves · Oct 3 – Nov 7

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 24) and first fall frost (Oct 17) 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 84309 came on Mar 20 — 17 days earlier than the 1991–2020 average (Apr 6).

average
Apr 62026
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 6b in Utah

549 plants native to the lower 48 states, recorded in Utah, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Deweyville, UT.

Soil in Deweyville, UT

The soil mapped at the center of ZIP 84309 is Kidman — fine sandy loam, well drained.

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

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupAwater soaks in fast

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Kidman fine sandy loam, 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 84309; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Deweyville, UT

Summer high91 °Faverage high, July

Winter low19 °Faverage low, January

Hot days45days a year at 90 °F or more

Freezing nights132nights a year at 32 °F or less

Growing degree days3,035base 50 °F — the season’s usable heat

Longest day15 h 12 mindaylight on June 21

Shortest day9 h 09 mindaylight on December 21

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

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: Tremonton, UT (3 mi away); precipitation: Garland 1.0 Se, UT (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

843146b

Honeyville, UT · 4 mi

843126b

Garland, UT · 5 mi

843066a

Collinston, UT · 5 mi

Bear River City, UT · 7 mi

843116a

Fielding, UT · 7 mi

843026b

Brigham City, UT · 9 mi

Utah planting zones →

Questions about 84309

What planting zone is ZIP code 84309?

ZIP code 84309 (Deweyville, UT) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Deweyville, UT?

The median last spring frost (32 °F) near 84309 is April 24; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Tremonton station.

When is the first frost in Deweyville, UT?

The median first fall frost near 84309 is October 17, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 84309?

Start tomato seeds indoors around Feb 27 – Mar 13 and set transplants outside around May 1 – May 15, one to three weeks after the median last frost.

How much rain and snow does 84309 get?

About 17.4 inches of precipitation a year (NOAA 1991–2020 normals, Garland 1.0 Se station).

How hot do summers get in Deweyville, UT?

The average high peaks at 91 °F in July, with about 45 days a year at 90 °F or more.

What kind of soil does 84309 have?

The USDA soil survey maps Kidman at the center of ZIP 84309: fine sandy loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Deweyville, UT in 2026?

Spring leaf-out near 84309 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 Deweyville, UT?

Long-day onions: the longest day near 84309 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 84309 change?

Yes. The 2012 USDA map put 84309 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.