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

Planting zone for 84302 — Brigham City, UT

ZIP code 84302 (Brigham City, Box Elder County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 5 and the first fall frost October 5.

Where ZIP 84302 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 5

First frostOct 5

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Brigham City, 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 Brigham City, UT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 5median — 50% chance of a later frost

Safe for tender plantsMay 29only 10% chance of frost after

First fall frostOctober 5median — 10% chance by Sep 20

Growing season150 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around October 17.

From the NOAA station Brigham City Waste Plt, UT — 4 miles away, elevation 4,239 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 84302

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 24 – Apr 7

SpinachSow outdoors · Mar 24 – Apr 14

Broccoli, cabbageStart indoors · Feb 24 – Mar 10

Broccoli, cabbageTransplant · Apr 14 – Apr 28

Onion setsPlant outdoors · Apr 7 – Apr 21

PotatoesPlant outdoors · Apr 14 – Apr 28

LettuceSow outdoors · Apr 7 – Apr 21

Carrots, beetsSow outdoors · Apr 14 – Apr 28

TomatoesStart indoors · Mar 10 – Mar 24

TomatoesTransplant · May 12 – May 26

Peppers, eggplantStart indoors · Feb 24 – Mar 10

Peppers, eggplantTransplant · May 19 – Jun 2

BeansSow outdoors · May 12 – May 26

Sweet cornSow outdoors · May 12 – May 26

Cucumbers, squashSow outdoors · May 12 – May 26

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 5) 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 84302 came on Mar 16 — 16 days earlier than the 1991–2020 average (Apr 1).

average
Apr 12026
Mar 16

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).

Soil in Brigham City, UT

The soil mapped at the center of ZIP 84302 is Roshe Springs — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables

pH7.6slightly alkaline; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter7%high

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Roshe Springs silt loam, 0 to 3 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 84302; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Brigham City, UT

Summer high91 °Faverage high, July

Winter low18 °Faverage low, January

Hot days45days a year at 90 °F or more

Freezing nights149nights a year at 32 °F or less

Growing degree days2,761base 50 °F — the season’s usable heat

Longest day15 h 12 mindaylight on June 21

Shortest day9 h 09 mindaylight on December 21

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

Precipitation15.5 inper year, rain and melted snow

Snowfall38 inper year; 52 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: Brigham City Waste Plt, UT (4 mi away); precipitation: Brigham City Waste Plt, UT (4 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.

843016b

Bear River City, UT · 4 mi

843146b

Honeyville, UT · 5 mi

843396a

Wellsville, UT · 6 mi

843246a

Mantua, UT · 8 mi

843096b

Deweyville, UT · 9 mi

Millville, UT · 14 mi

Utah planting zones →

Questions about 84302

What planting zone is ZIP code 84302?

ZIP code 84302 (Brigham City, 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 Brigham City, UT?

The median last spring frost (32 °F) near 84302 is May 5; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Brigham City Waste Plt station.

When is the first frost in Brigham City, UT?

The median first fall frost near 84302 is October 5, giving a median frost-free growing season of 150 days.

When should I plant tomatoes in 84302?

Start tomato seeds indoors around Mar 10 – Mar 24 and set transplants outside around May 12 – May 26, one to three weeks after the median last frost.

How much rain and snow does 84302 get?

About 15.5 inches of precipitation a year and 38 inches of snowfall (NOAA 1991–2020 normals, Brigham City Waste Plt station).

How hot do summers get in Brigham City, UT?

The average high peaks at 91 °F in July, with about 45 days a year at 90 °F or more.

What kind of soil does 84302 have?

The USDA soil survey maps Roshe Springs at the center of ZIP 84302: silt loam, poorly drained, pH about 7.6 (slightly alkaline).

Did spring come early in Brigham City, UT in 2026?

Spring leaf-out near 84302 came on Mar 16 in 2026, 16 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Brigham City, UT?

Long-day onions: the longest day near 84302 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 84302 change?

Yes. The 2012 USDA map put 84302 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.