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

Planting zone for 97830 — Fossil, OR

ZIP code 97830 (Fossil, Wheeler County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is June 3 and the first fall frost September 14.

Where ZIP 97830 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostJun 3

First frostSep 14

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Fossil, OR…

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 Fossil, OR

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 3median — 50% chance of a later frost

Safe for tender plantsJuly 3only 10% chance of frost after

First fall frostSeptember 14median — 10% chance by Aug 25

Growing season98 daysfrost-free, median

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

From the NOAA station Fossil, OR — 2 miles away, elevation 2,651 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 97830

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 22 – May 6

SpinachSow outdoors · Apr 22 – May 13

Broccoli, cabbageStart indoors · Mar 25 – Apr 8

Broccoli, cabbageTransplant · May 13 – May 27

Onion setsPlant outdoors · May 6 – May 20

PotatoesPlant outdoors · May 13 – May 27

LettuceSow outdoors · May 6 – May 20

Carrots, beetsSow outdoors · May 13 – May 27

TomatoesStart indoors · Apr 8 – Apr 22

TomatoesTransplant · Jun 10 – Jun 24

Peppers, eggplantStart indoors · Mar 25 – Apr 8

Peppers, eggplantTransplant · Jun 17 – Jul 1

BeansSow outdoors · Jun 10 – Jun 24

Sweet cornSow outdoors · Jun 10 – Jun 24

Cucumbers, squashSow outdoors · Jun 10 – Jun 24

Fall lettuce, spinachSow outdoors · Jul 20 – Aug 3

GarlicPlant cloves · Aug 31 – Oct 5

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 3) and first fall frost (Sep 14) 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 97830 came on Mar 15 — 20 days earlier than the 1991–2020 average (Apr 4).

average
Apr 42026
Mar 15

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 Fossil, OR

The soil mapped at the center of ZIP 97830 is Kishwalk — very stony loam, well drained.

TextureVery stony loama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Kishwalk-Kaskela-Gwinly complex, landslides, 5 to 35 percent north 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 97830; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fossil, OR

Summer high85 °Faverage high, July

Winter low24 °Faverage low, December

Hot days27days a year at 90 °F or more

Freezing nights127nights a year at 32 °F or less

Growing degree days1,603base 50 °F — the season’s usable heat

Longest day15 h 37 mindaylight on June 21

Shortest day8 h 46 mindaylight on December 21

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

Precipitation15.1 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: Fossil, OR (2 mi away); precipitation: Fossil, OR (2 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.

Oregon planting zones →

Questions about 97830

What planting zone is ZIP code 97830?

ZIP code 97830 (Fossil, OR) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Fossil, OR?

The median last spring frost (32 °F) near 97830 is June 3; after July 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Fossil station.

When is the first frost in Fossil, OR?

The median first fall frost near 97830 is September 14, giving a median frost-free growing season of 98 days.

When should I plant tomatoes in 97830?

Start tomato seeds indoors around Apr 8 – Apr 22 and set transplants outside around Jun 10 – Jun 24, one to three weeks after the median last frost.

How much rain and snow does 97830 get?

About 15.1 inches of precipitation a year (NOAA 1991–2020 normals, Fossil station).

How hot do summers get in Fossil, OR?

The average high peaks at 85 °F in July, with about 27 days a year at 90 °F or more.

What kind of soil does 97830 have?

The USDA soil survey maps Kishwalk at the center of ZIP 97830: very stony loam, well drained, pH about 7.0 (neutral).

Did spring come early in Fossil, OR in 2026?

Spring leaf-out near 97830 came on Mar 15 in 2026, 20 days earlier than the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Fossil, OR?

Long-day onions: the longest day near 97830 is 15 h 37 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 97830 change?

Yes. The 2012 USDA map put 97830 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.