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

Planting zone for 95666 — Pioneer, CA

ZIP code 95666 (Pioneer, Amador County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is April 26 and the first fall frost November 2.

Where ZIP 95666 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.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostApr 26
First frostNov 2
2012 zone9a

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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Pioneer, CA…

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 Pioneer, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 26median — 50% chance of a later frost
Safe for tender plantsMay 19only 10% chance of frost after
First fall frostNovember 2median — 10% chance by Oct 14
Growing season191 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around November 22.

From the NOAA station Pacific House, CA — 17 miles away, elevation 3,452 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 95666

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 15 – Mar 29
SpinachSow outdoors · Mar 15 – Apr 5
Broccoli, cabbageStart indoors · Feb 15 – Mar 1
Broccoli, cabbageTransplant · Apr 5 – Apr 19
Onion setsPlant outdoors · Mar 29 – Apr 12
PotatoesPlant outdoors · Apr 5 – Apr 19
LettuceSow outdoors · Mar 29 – Apr 12
Carrots, beetsSow outdoors · Apr 5 – Apr 19
TomatoesStart indoors · Mar 1 – Mar 15
TomatoesTransplant · May 3 – May 17
Peppers, eggplantStart indoors · Feb 15 – Mar 1
Peppers, eggplantTransplant · May 10 – May 24
BeansSow outdoors · May 3 – May 17
Sweet cornSow outdoors · May 3 – May 17
Cucumbers, squashSow outdoors · May 3 – May 17
Fall lettuce, spinachSow outdoors · Sep 7 – Sep 21
GarlicPlant cloves · Oct 19 – Nov 23
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Nov 2) 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 95666 came on Feb 5 — 27 days earlier than the 1991–2020 average (Mar 4).

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 Pioneer, CA

The soil mapped at the center of ZIP 95666 is McCarthy — gravelly sandy loam, well drained.

TextureGravelly sandy loamdrains and warms fast; dries out and needs more feeding
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter6%high
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: McCarthy gravelly sandy loam, 30 to 50 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 95666; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Pioneer, CA

Summer high90 °Faverage high, July
Winter low31 °Faverage low, February
Hot days58days a year at 90 °F or more
Freezing nights97nights a year at 32 °F or less
Growing degree days2,775base 50 °F — the season’s usable heat
Longest day14 h 52 mindaylight on June 21
Shortest day9 h 28 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation40.6 inper year, rain and melted snow
Snowfall4 inper year; 1 days with snow on the ground

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 44 °F, low 32 °F 44°32° JanFebruary: average high 50 °F, low 31 °F 50°31° FebMarch: average high 56 °F, low 33 °F 56°33° MarApril: average high 63 °F, low 36 °F 63°36° AprMay: average high 72 °F, low 42 °F 72°42° MayJune: average high 82 °F, low 47 °F 82°47° JunJuly: average high 90 °F, low 53 °F 90°53° JulAugust: average high 89 °F, low 53 °F 89°53° AugSeptember: average high 83 °F, low 49 °F 83°49° SepOctober: average high 66 °F, low 41 °F 66°41° OctNovember: average high 51 °F, low 35 °F 51°35° NovDecember: average high 43 °F, low 31 °F 43°31° Dec

Precipitation by month inches · ❄ = snowfall

0″2″4″6″8″January: 7.34 in precipitation, 0.1 in snowfall 7.3 JanFebruary: 6.91 in precipitation, 1.7 in snowfall 6.9❄2 FebMarch: 6.39 in precipitation, 1.5 in snowfall 6.4❄2 MarApril: 3.36 in precipitation 3.4 AprMay: 2.14 in precipitation 2.1 MayJune: 0.49 in precipitation 0.5 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.04 in precipitation 0.0 AugSeptember: 0.27 in precipitation 0.3 SepOctober: 2.15 in precipitation 2.1 OctNovember: 3.95 in precipitation 4.0 NovDecember: 7.52 in precipitation, 0.4 in snowfall 7.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Pacific House, CA (17 mi away); precipitation: W Pt, CA (16 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

956849a
Somerset, CA · 9 mi
956368b
Grizzly Flats, CA · 10 mi
952559a
West Point, CA · 12 mi
952578b
Wilseyville, CA · 13 mi
956447a
Kit Carson, CA · 15 mi
957268b
Pollock Pines, CA · 16 mi
956899a
Volcano, CA · 16 mi
952489a
Rail Road Flat, CA · 17 mi

California planting zones →

Questions about 95666

What planting zone is ZIP code 95666?

ZIP code 95666 (Pioneer, CA) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Pioneer, CA?

The median last spring frost (32 °F) near 95666 is April 26; after May 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pacific House station.

When is the first frost in Pioneer, CA?

The median first fall frost near 95666 is November 2, giving a median frost-free growing season of 191 days.

When should I plant tomatoes in 95666?

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

How much rain and snow does 95666 get?

About 40.6 inches of precipitation a year and 4 inches of snowfall (NOAA 1991–2020 normals, W Pt station).

How hot do summers get in Pioneer, CA?

The average high peaks at 90 °F in July, with about 58 days a year at 90 °F or more.

What kind of soil does 95666 have?

The USDA soil survey maps McCarthy at the center of ZIP 95666: gravelly sandy loam, well drained, pH about 6.1 (slightly acidic).

Did spring come early in Pioneer, CA in 2026?

Spring leaf-out near 95666 came on Feb 5 in 2026, 27 days earlier than the 1991–2020 average (Mar 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Pioneer, CA?

Intermediate onions: the longest day near 95666 is 14 h 52 min, so day-neutral types bulb best; long-day varieties may not bulb fully.