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

Planting zone for 84772 — Summit, UT

ZIP code 84772 (Summit, Iron County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is June 21 and the first fall frost September 12.

Where ZIP 84772 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 frostJun 21

First frostSep 12

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 Summit, 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 Summit, UT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 21median — 50% chance of a later frost

Safe for tender plantsJuly 6only 10% chance of frost after

First fall frostSeptember 12median — 10% chance by Sep 1

Growing season82 daysfrost-free, median

A hard freeze (28 °F) usually ends around June 7 and returns around September 22.

From the NOAA station Brian Head, UT — 9 miles away, elevation 9,771 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 84772

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 10 – May 24

SpinachSow outdoors · May 10 – May 31

Broccoli, cabbageStart indoors · Apr 12 – Apr 26

Broccoli, cabbageTransplant · May 31 – Jun 14

Onion setsPlant outdoors · May 24 – Jun 7

PotatoesPlant outdoors · May 31 – Jun 14

LettuceSow outdoors · May 24 – Jun 7

Carrots, beetsSow outdoors · May 31 – Jun 14

TomatoesStart indoors · Apr 26 – May 10

TomatoesTransplant · Jun 28 – Jul 12

Peppers, eggplantStart indoors · Apr 12 – Apr 26

Peppers, eggplantTransplant · Jul 5 – Jul 19

BeansSow outdoors · Jun 28 – Jul 12

Sweet cornSow outdoors · Jun 28 – Jul 12

Cucumbers, squashSow outdoors · Jun 28 – Jul 12

Fall lettuce, spinachSow outdoors · Jul 18 – Aug 1

GarlicPlant cloves · Aug 29 – Oct 3

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 21) and first fall frost (Sep 12) 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 84772 came on Mar 10 — 18 days earlier than the 1991–2020 average (Mar 28).

average
Mar 282026
Mar 10

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 Summit, UT.

Soil in Summit, UT

The soil mapped at the center of ZIP 84772 is Braffits — loam, well drained.

TextureLoama good balance for most vegetables

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Braffits 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 84772; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Summit, UT

Summer high71 °Faverage high, July

Winter low10 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights255nights a year at 32 °F or less

Growing degree days549base 50 °F — the season’s usable heat

Longest day14 h 47 mindaylight on June 21

Shortest day9 h 33 mindaylight on December 21

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

Precipitation12.1 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: Brian Head, UT (9 mi away); precipitation: Summit, UT (within 1 mile). 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.

847616a

Parowan, UT · 6 mi

847216b

Cedar City, UT · 10 mi

847196a

Brian Head, UT · 13 mi

847606a

Paragonah, UT · 19 mi

847426b

Kanarraville, UT · 22 mi

847206b

Cedar City, UT · 23 mi

847626a

Duck Creek Village, UT · 23 mi

847577a

New Harmony, UT · 29 mi

Utah planting zones →

Questions about 84772

What planting zone is ZIP code 84772?

ZIP code 84772 (Summit, 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 Summit, UT?

The median last spring frost (32 °F) near 84772 is June 21; after July 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Brian Head station.

When is the first frost in Summit, UT?

The median first fall frost near 84772 is September 12, giving a median frost-free growing season of 82 days.

When should I plant tomatoes in 84772?

Start tomato seeds indoors around Apr 26 – May 10 and set transplants outside around Jun 28 – Jul 12, one to three weeks after the median last frost.

How much rain and snow does 84772 get?

About 12.1 inches of precipitation a year (NOAA 1991–2020 normals, Summit station).

How hot do summers get in Summit, UT?

The average high peaks at 71 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 84772 have?

The USDA soil survey maps Braffits at the center of ZIP 84772: loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Summit, UT in 2026?

Spring leaf-out near 84772 came on Mar 10 in 2026, 18 days earlier than the 1991–2020 average (Mar 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Summit, UT?

Intermediate onions: the longest day near 84772 is 14 h 47 min, so day-neutral types bulb best; long-day varieties may not bulb fully.