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

Planting zone for 84008 — Bonanza, UT

ZIP code 84008 (Bonanza, Uintah County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 12 and the first fall frost October 5.

Where ZIP 84008 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 12

First frostOct 5

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 Bonanza, 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 Bonanza, UT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 12median — 50% chance of a later frost

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

First fall frostOctober 5median — 10% chance by Sep 23

Growing season146 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 16.

From the NOAA station Dinosaur Nm, CO — 19 miles away, elevation 5,962 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 84008

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 31 – Apr 14

SpinachSow outdoors · Mar 31 – Apr 21

Broccoli, cabbageStart indoors · Mar 3 – Mar 17

Broccoli, cabbageTransplant · Apr 21 – May 5

Onion setsPlant outdoors · Apr 14 – Apr 28

PotatoesPlant outdoors · Apr 21 – May 5

LettuceSow outdoors · Apr 14 – Apr 28

Carrots, beetsSow outdoors · Apr 21 – May 5

TomatoesStart indoors · Mar 17 – Mar 31

TomatoesTransplant · May 19 – Jun 2

Peppers, eggplantStart indoors · Mar 3 – Mar 17

Peppers, eggplantTransplant · May 26 – Jun 9

BeansSow outdoors · May 19 – Jun 2

Sweet cornSow outdoors · May 19 – Jun 2

Cucumbers, squashSow outdoors · May 19 – Jun 2

Fall lettuce, spinachSow outdoors · Aug 10 – Aug 24

GarlicPlant cloves · Sep 21 – Oct 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 12) and first fall frost (Oct 5) 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 84008 came on Mar 18 — 14 days earlier than the 1991–2020 average (Apr 1).

average
Apr 12026
Mar 18

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.

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 Bonanza, UT.

Soil in Bonanza, UT

The soil mapped at the center of ZIP 84008 is Walknolls — very channery loam, well drained.

TextureVery channery loama good balance for most vegetables

pH8.5alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Walknolls-Gilston association, 2 to 25 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 84008; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Bonanza, UT

Summer high89 °Faverage high, July

Winter low12 °Faverage low, January

Hot days41days a year at 90 °F or more

Freezing nights164nights a year at 32 °F or less

Growing degree days2,578base 50 °F — the season’s usable heat

Longest day15 h 01 mindaylight on June 21

Shortest day9 h 19 mindaylight on December 21

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

Precipitation10.7 inper year, rain and melted snow

Snowfall26 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Dinosaur Nm, CO (19 mi away); precipitation: Dinosaur Nm, CO (19 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.

Fort Duchesne, UT · 39 mi

840395b

Lapoint, UT · 43 mi

Utah planting zones →

Questions about 84008

What planting zone is ZIP code 84008?

ZIP code 84008 (Bonanza, 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 Bonanza, UT?

The median last spring frost (32 °F) near 84008 is May 12; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dinosaur Nm station.

When is the first frost in Bonanza, UT?

The median first fall frost near 84008 is October 5, giving a median frost-free growing season of 146 days.

When should I plant tomatoes in 84008?

Start tomato seeds indoors around Mar 17 – Mar 31 and set transplants outside around May 19 – Jun 2, one to three weeks after the median last frost.

How much rain and snow does 84008 get?

About 10.7 inches of precipitation a year and 26 inches of snowfall (NOAA 1991–2020 normals, Dinosaur Nm station).

How hot do summers get in Bonanza, UT?

The average high peaks at 89 °F in July, with about 41 days a year at 90 °F or more.

What kind of soil does 84008 have?

The USDA soil survey maps Walknolls at the center of ZIP 84008: very channery loam, well drained, pH about 8.5 (alkaline).

Did spring come early in Bonanza, UT in 2026?

Spring leaf-out near 84008 came on Mar 18 in 2026, 14 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Bonanza, UT?

Long-day onions: the longest day near 84008 is 15 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 84008 change?

Yes. The 2012 USDA map put 84008 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.