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

Planting zone for 84790 — Saint George, UT

ZIP code 84790 (Saint George, Washington County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 14 and the first fall frost November 10.

Where ZIP 84790 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.

Zone8b15 to 20 °F
Coldest night−9.4 to −6.7 °C
Last frostMar 14
First frostNov 10
2012 zone8a

Was 8a 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 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Saint George, 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 Saint George, UT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 14median — 50% chance of a later frost
Safe for tender plantsApril 6only 10% chance of frost after
First fall frostNovember 10median — 10% chance by Oct 27
Growing season239 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 27 and returns around November 20.

From the NOAA station St George, UT — 6 miles away, elevation 2,858 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 84790

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 31 – Feb 14
SpinachSow outdoors · Jan 31 – Feb 21
Broccoli, cabbageStart indoors · Jan 3 – Jan 17
Broccoli, cabbageTransplant · Feb 21 – Mar 7
Onion setsPlant outdoors · Feb 14 – Feb 28
PotatoesPlant outdoors · Feb 21 – Mar 7
LettuceSow outdoors · Feb 14 – Feb 28
Carrots, beetsSow outdoors · Feb 21 – Mar 7
TomatoesStart indoors · Jan 17 – Jan 31
TomatoesTransplant · Mar 21 – Apr 4
Peppers, eggplantStart indoors · Jan 3 – Jan 17
Peppers, eggplantTransplant · Mar 28 – Apr 11
BeansSow outdoors · Mar 21 – Apr 4
Sweet cornSow outdoors · Mar 21 – Apr 4
Cucumbers, squashSow outdoors · Mar 21 – Apr 4
Fall lettuce, spinachSow outdoors · Sep 15 – Sep 29
GarlicPlant cloves · Oct 27 – Dec 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 14) and first fall frost (Nov 10) 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 84790 came on Feb 3 — 7 days earlier than the 1991–2020 average (Feb 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 8b in Utah

581 plants native to the lower 48 states, recorded in Utah, and rated by the USDA to survive 15 °F or colder — the bottom of zone 8b. Each links to its USDA PLANTS profile.

Trees 31

American beech80 ft · blooms mid spring · low shade tolerance · to −44 °FArizona cypress50 ft · blooms spring · low shade tolerance · to −23 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack walnut100 ft · blooms late spring · high shade tolerance · to −28 °F

Shrubs 119

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FApache plume6 ft · blooms late spring · high shade tolerance · to −23 °F

Wildflowers & perennials 260

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 158

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °Farctic bluegrass2 ft · high shade tolerance · to −62 °F

Vines 3

trumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

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 Saint George, UT.

Soil in Saint George, UT

The soil mapped at the center of ZIP 84790 is Hobog — very cobbly loam, well drained.

TextureVery cobbly loama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Hobog-Rock land association.

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 84790; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint George, UT

Summer high102 °Faverage high, July
Winter low28 °Faverage low, January
Hot days128days a year at 90 °F or more
Freezing nights63nights a year at 32 °F or less
Growing degree days5,546base 50 °F — the season’s usable heat
Longest day14 h 42 mindaylight on June 21
Shortest day9 h 37 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation9.3 inper year, rain and melted snow
Snowfall1 inper year

Average high and low, by month

20°30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 54 °F, low 28 °F 54°28° JanFebruary: average high 59 °F, low 32 °F 59°32° FebMarch: average high 68 °F, low 39 °F 68°39° MarApril: average high 75 °F, low 46 °F 75°46° AprMay: average high 85 °F, low 56 °F 85°56° MayJune: average high 96 °F, low 65 °F 96°65° JunJuly: average high 102 °F, low 72 °F 102°72° JulAugust: average high 100 °F, low 70 °F 100°70° AugSeptember: average high 92 °F, low 61 °F 92°61° SepOctober: average high 79 °F, low 47 °F 79°47° OctNovember: average high 64 °F, low 35 °F 64°35° NovDecember: average high 53 °F, low 28 °F 53°28° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″January: 1.22 in precipitation, 0.5 in snowfall 1.2❄1 JanFebruary: 1.38 in precipitation, 0.5 in snowfall 1.4❄1 FebMarch: 1.02 in precipitation, 0.2 in snowfall 1.0 MarApril: 0.66 in precipitation 0.7 AprMay: 0.33 in precipitation 0.3 MayJune: 0.16 in precipitation 0.2 JunJuly: 0.50 in precipitation 0.5 JulAugust: 1.07 in precipitation 1.1 AugSeptember: 0.67 in precipitation 0.7 SepOctober: 0.77 in precipitation 0.8 OctNovember: 0.67 in precipitation 0.7 NovDecember: 0.86 in precipitation 0.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: St George, UT (6 mi away); precipitation: St George, UT (6 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.

847718b
Saint George, UT · 4 mi
847918b
Saint George, UT · 4 mi
847708b
Saint George, UT · 8 mi
847808b
Washington, UT · 8 mi
847388b
Ivins, UT · 14 mi
847838a
Dammeron Valley, UT · 17 mi
847468b
Leeds, UT · 18 mi
864328b
Littlefield, AZ · 19 mi

All 4 ZIP codes in Saint George → · Utah planting zones →

Questions about 84790

What planting zone is ZIP code 84790?

ZIP code 84790 (Saint George, UT) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Saint George, UT?

The median last spring frost (32 °F) near 84790 is March 14; after April 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, St George station.

When is the first frost in Saint George, UT?

The median first fall frost near 84790 is November 10, giving a median frost-free growing season of 239 days.

When should I plant tomatoes in 84790?

Start tomato seeds indoors around Jan 17 – Jan 31 and set transplants outside around Mar 21 – Apr 4, one to three weeks after the median last frost.

How much rain and snow does 84790 get?

About 9.3 inches of precipitation a year and 1 inches of snowfall (NOAA 1991–2020 normals, St George station).

How hot do summers get in Saint George, UT?

The average high peaks at 102 °F in July, with about 128 days a year at 90 °F or more.

What kind of soil does 84790 have?

The USDA soil survey maps Hobog at the center of ZIP 84790: very cobbly loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Saint George, UT in 2026?

Spring leaf-out near 84790 came on Feb 3 in 2026, 7 days earlier than the 1991–2020 average (Feb 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint George, UT?

Intermediate onions: the longest day near 84790 is 14 h 42 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 84790 change?

Yes. The 2012 USDA map put 84790 in zone 8a; the 2023 map puts it in zone 8b. The newer map uses 1991–2020 data and more weather stations.