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

Planting zone for 84521 — Elmo, UT

ZIP code 84521 (Elmo, Emery County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 27 and the first fall frost September 26.

Where ZIP 84521 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 27

First frostSep 26

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Elmo, 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 Elmo, UT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 27median — 50% chance of a later frost

Safe for tender plantsJune 11only 10% chance of frost after

First fall frostSeptember 26median — 10% chance by Sep 11

Growing season122 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 9 and returns around October 5.

From the NOAA station Wellington 3 E, UT — 10 miles away, elevation 5,401 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 84521

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 15 – Apr 29

SpinachSow outdoors · Apr 15 – May 6

Broccoli, cabbageStart indoors · Mar 18 – Apr 1

Broccoli, cabbageTransplant · May 6 – May 20

Onion setsPlant outdoors · Apr 29 – May 13

PotatoesPlant outdoors · May 6 – May 20

LettuceSow outdoors · Apr 29 – May 13

Carrots, beetsSow outdoors · May 6 – May 20

TomatoesStart indoors · Apr 1 – Apr 15

TomatoesTransplant · Jun 3 – Jun 17

Peppers, eggplantStart indoors · Mar 18 – Apr 1

Peppers, eggplantTransplant · Jun 10 – Jun 24

BeansSow outdoors · Jun 3 – Jun 17

Sweet cornSow outdoors · Jun 3 – Jun 17

Cucumbers, squashSow outdoors · Jun 3 – Jun 17

Fall lettuce, spinachSow outdoors · Aug 1 – Aug 15

GarlicPlant cloves · Sep 12 – Oct 17

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 27) and first fall frost (Sep 26) 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 84521 came on Mar 17 — 12 days earlier than the 1991–2020 average (Mar 29).

average
Mar 292026
Mar 17

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 Elmo, UT.

Soil in Elmo, UT

The soil mapped at the center of ZIP 84521 is Chipeta — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Chipeta-Persayo-Killpack complex, 3 to 20 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 84521; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Elmo, UT

Summer high91 °Faverage high, July

Winter low8 °Faverage low, January

Hot days53days a year at 90 °F or more

Freezing nights200nights a year at 32 °F or less

Growing degree days2,328base 50 °F — the season’s usable heat

Longest day14 h 57 mindaylight on June 21

Shortest day9 h 23 mindaylight on December 21

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

Precipitation9.1 inper year, rain and melted snow

Snowfall22 inper year; 37 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Wellington 3 E, UT (10 mi away); precipitation: Wellington 3 E, UT (10 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.

Huntington, UT · 17 mi

845136a

Castle Dale, UT · 17 mi

845296b

Kenilworth, UT · 20 mi

845266a

Helper, UT · 21 mi

845376a

Orangeville, UT · 23 mi

845166a

Clawson, UT · 26 mi

Utah planting zones →

Questions about 84521

What planting zone is ZIP code 84521?

ZIP code 84521 (Elmo, 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 Elmo, UT?

The median last spring frost (32 °F) near 84521 is May 27; after June 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wellington 3 E station.

When is the first frost in Elmo, UT?

The median first fall frost near 84521 is September 26, giving a median frost-free growing season of 122 days.

When should I plant tomatoes in 84521?

Start tomato seeds indoors around Apr 1 – Apr 15 and set transplants outside around Jun 3 – Jun 17, one to three weeks after the median last frost.

How much rain and snow does 84521 get?

About 9.1 inches of precipitation a year and 22 inches of snowfall (NOAA 1991–2020 normals, Wellington 3 E station).

How hot do summers get in Elmo, UT?

The average high peaks at 91 °F in July, with about 53 days a year at 90 °F or more.

What kind of soil does 84521 have?

The USDA soil survey maps Chipeta at the center of ZIP 84521: silty clay loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Elmo, UT in 2026?

Spring leaf-out near 84521 came on Mar 17 in 2026, 12 days earlier than the 1991–2020 average (Mar 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Elmo, UT?

Intermediate onions: the longest day near 84521 is 14 h 57 min, so day-neutral types bulb best; long-day varieties may not bulb fully.