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

Planting zone for 84628 — Eureka, UT

ZIP code 84628 (Eureka, Juab County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 15 and the first fall frost October 1.

Where ZIP 84628 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 frostMay 15

First frostOct 1

2012 zone6b

Same zone as on the 2012 map. 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 Eureka, 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 Eureka, UT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 15median — 50% chance of a later frost

Safe for tender plantsJune 5only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 17

Growing season137 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 2 and returns around October 10.

From the NOAA station Little Sahara Rec Area, UT — 17 miles away, elevation 5,230 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 84628

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 3 – Apr 17

SpinachSow outdoors · Apr 3 – Apr 24

Broccoli, cabbageStart indoors · Mar 6 – Mar 20

Broccoli, cabbageTransplant · Apr 24 – May 8

Onion setsPlant outdoors · Apr 17 – May 1

PotatoesPlant outdoors · Apr 24 – May 8

LettuceSow outdoors · Apr 17 – May 1

Carrots, beetsSow outdoors · Apr 24 – May 8

TomatoesStart indoors · Mar 20 – Apr 3

TomatoesTransplant · May 22 – Jun 5

Peppers, eggplantStart indoors · Mar 6 – Mar 20

Peppers, eggplantTransplant · May 29 – Jun 12

BeansSow outdoors · May 22 – Jun 5

Sweet cornSow outdoors · May 22 – Jun 5

Cucumbers, squashSow outdoors · May 22 – Jun 5

Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20

GarlicPlant cloves · Sep 17 – Oct 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 15) and first fall frost (Oct 1) 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 84628 came on Mar 20 — 20 days earlier than the 1991–2020 average (Apr 9).

average
Apr 92026
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 Eureka, UT.

Soil in Eureka, UT

The soil mapped at the center of ZIP 84628 is Lodar — very cobbly loam, somewhat excessively drained.

TextureVery cobbly loama good balance for most vegetables

pH8.5alkaline; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Rock outcrop-Lodar complex, 30 to 70 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 84628; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Eureka, UT

Summer high93 °Faverage high, July

Winter low16 °Faverage low, January

Hot days64days a year at 90 °F or more

Freezing nights173nights a year at 32 °F or less

Growing degree days2,923base 50 °F — the season’s usable heat

Longest day15 h 00 mindaylight on June 21

Shortest day9 h 20 mindaylight on December 21

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

Precipitation25.5 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: Little Sahara Rec Area, UT (17 mi away); precipitation: Vernon Creek, UT (15 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Santaquin, UT · 18 mi

Cedar Valley, UT · 25 mi

Utah planting zones →

Questions about 84628

What planting zone is ZIP code 84628?

ZIP code 84628 (Eureka, 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 Eureka, UT?

The median last spring frost (32 °F) near 84628 is May 15; after June 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Little Sahara Rec Area station.

When is the first frost in Eureka, UT?

The median first fall frost near 84628 is October 1, giving a median frost-free growing season of 137 days.

When should I plant tomatoes in 84628?

Start tomato seeds indoors around Mar 20 – Apr 3 and set transplants outside around May 22 – Jun 5, one to three weeks after the median last frost.

How much rain and snow does 84628 get?

About 25.5 inches of precipitation a year (NOAA 1991–2020 normals, Vernon Creek station).

How hot do summers get in Eureka, UT?

The average high peaks at 93 °F in July, with about 64 days a year at 90 °F or more.

What kind of soil does 84628 have?

The USDA soil survey maps Lodar at the center of ZIP 84628: very cobbly loam, somewhat excessively drained, pH about 8.5 (alkaline).

Did spring come early in Eureka, UT in 2026?

Spring leaf-out near 84628 came on Mar 20 in 2026, 20 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Eureka, UT?

Long-day onions: the longest day near 84628 is 15 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).