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

Planting zone for 95946 — Penn Valley, CA

ZIP code 95946 (Penn Valley, Nevada County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is April 10 and the first fall frost November 13.

Where ZIP 95946 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.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostApr 10
First frostNov 13
2012 zone9a

Was 9a 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 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Penn Valley, 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 Penn Valley, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 10median — 50% chance of a later frost
Safe for tender plantsApril 30only 10% chance of frost after
First fall frostNovember 13median — 10% chance by Oct 26
Growing season215 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 9 and returns around December 1.

From the NOAA station Grass Valley #2, CA — 8 miles away, elevation 2,402 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 95946

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 27 – Mar 13
SpinachSow outdoors · Feb 27 – Mar 20
Broccoli, cabbageStart indoors · Jan 30 – Feb 13
Broccoli, cabbageTransplant · Mar 20 – Apr 3
Onion setsPlant outdoors · Mar 13 – Mar 27
PotatoesPlant outdoors · Mar 20 – Apr 3
LettuceSow outdoors · Mar 13 – Mar 27
Carrots, beetsSow outdoors · Mar 20 – Apr 3
TomatoesStart indoors · Feb 13 – Feb 27
TomatoesTransplant · Apr 17 – May 1
Peppers, eggplantStart indoors · Jan 30 – Feb 13
Peppers, eggplantTransplant · Apr 24 – May 8
BeansSow outdoors · Apr 17 – May 1
Sweet cornSow outdoors · Apr 17 – May 1
Cucumbers, squashSow outdoors · Apr 17 – May 1
Fall lettuce, spinachSow outdoors · Sep 18 – Oct 2
GarlicPlant cloves · Oct 30 – Dec 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 10) and first fall frost (Nov 13) 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 95946 came on Jan 29 — 4 days earlier than the 1991–2020 average (Feb 2).

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 Penn Valley, CA

The soil mapped at the center of ZIP 95946 is Sierra — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH6.3slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Sierra sandy loam, deep, 15 to 30 percent slopes, LRU 18XI.

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 95946; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Penn Valley, CA

Summer high88 °Faverage high, July
Winter low33 °Faverage low, January
Hot days36days a year at 90 °F or more
Freezing nights61nights a year at 32 °F or less
Growing degree days3,206base 50 °F — the season’s usable heat
Longest day14 h 56 mindaylight on June 21
Shortest day9 h 24 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation34.8 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 54 °F, low 33 °F 54°33° JanFebruary: average high 55 °F, low 34 °F 55°34° FebMarch: average high 58 °F, low 37 °F 58°37° MarApril: average high 63 °F, low 40 °F 63°40° AprMay: average high 71 °F, low 47 °F 71°47° MayJune: average high 80 °F, low 53 °F 80°53° JunJuly: average high 88 °F, low 58 °F 88°58° JulAugust: average high 87 °F, low 57 °F 87°57° AugSeptember: average high 82 °F, low 52 °F 82°52° SepOctober: average high 72 °F, low 44 °F 72°44° OctNovember: average high 60 °F, low 37 °F 60°37° NovDecember: average high 53 °F, low 33 °F 53°33° Dec

Precipitation by month inches

0″2″4″6″January: 5.95 in precipitation 6.0 JanFebruary: 6.10 in precipitation 6.1 FebMarch: 5.46 in precipitation 5.5 MarApril: 2.70 in precipitation 2.7 AprMay: 1.50 in precipitation 1.5 MayJune: 0.52 in precipitation 0.5 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.08 in precipitation 0.1 AugSeptember: 0.24 in precipitation 0.2 SepOctober: 1.78 in precipitation 1.8 OctNovember: 3.68 in precipitation 3.7 NovDecember: 6.78 in precipitation 6.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Grass Valley #2, CA (8 mi away); precipitation: Harry L Englebright Dam, CA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

959759a
Rough And Ready, CA · 3 mi
959779b
Smartsville, CA · 5 mi
959629b
Oregon House, CA · 8 mi
959499b
Grass Valley, CA · 9 mi
959189b
Browns Valley, CA · 9 mi
959039b
Beale Afb, CA · 10 mi
959249a
Cedar Ridge, CA · 10 mi
959359a
Dobbins, CA · 12 mi

California planting zones →

Questions about 95946

What planting zone is ZIP code 95946?

ZIP code 95946 (Penn Valley, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

When is the last frost in Penn Valley, CA?

The median last spring frost (32 °F) near 95946 is April 10; after April 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Grass Valley #2 station.

When is the first frost in Penn Valley, CA?

The median first fall frost near 95946 is November 13, giving a median frost-free growing season of 215 days.

When should I plant tomatoes in 95946?

Start tomato seeds indoors around Feb 13 – Feb 27 and set transplants outside around Apr 17 – May 1, one to three weeks after the median last frost.

How much rain and snow does 95946 get?

About 34.8 inches of precipitation a year (NOAA 1991–2020 normals, Harry L Englebright Dam station).

How hot do summers get in Penn Valley, CA?

The average high peaks at 88 °F in July, with about 36 days a year at 90 °F or more.

What kind of soil does 95946 have?

The USDA soil survey maps Sierra at the center of ZIP 95946: sandy loam, well drained, pH about 6.3 (slightly acidic).

Did spring come early in Penn Valley, CA in 2026?

Spring leaf-out near 95946 came on Jan 29 in 2026, 4 days earlier than the 1991–2020 average (Feb 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Penn Valley, CA?

Intermediate onions: the longest day near 95946 is 14 h 56 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 95946 change?

Yes. The 2012 USDA map put 95946 in zone 9a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.