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

Planting zone for 95640 — Ione, CA

ZIP code 95640 (Ione, Amador County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is March 4 and the first fall frost December 11.

Where ZIP 95640 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 frostMar 4

First frostDec 11

2012 zone9b

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 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Ione, 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 Ione, CA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 4median — 50% chance of a later frost

Safe for tender plantsApril 8only 10% chance of frost after

First fall frostDecember 11median — 10% chance by Nov 19

Growing season285 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 10 and returns around December 27.

From the NOAA station Sutter Hill Cdf, CA — 8 miles away, elevation 1,585 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 95640

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 21 – Feb 4

SpinachSow outdoors · Jan 21 – Feb 11

Broccoli, cabbageStart indoors · Dec 24 – Jan 7

Broccoli, cabbageTransplant · Feb 11 – Feb 25

Onion setsPlant outdoors · Feb 4 – Feb 18

PotatoesPlant outdoors · Feb 11 – Feb 25

LettuceSow outdoors · Feb 4 – Feb 18

Carrots, beetsSow outdoors · Feb 11 – Feb 25

TomatoesStart indoors · Jan 7 – Jan 21

TomatoesTransplant · Mar 11 – Mar 25

Peppers, eggplantStart indoors · Dec 24 – Jan 7

Peppers, eggplantTransplant · Mar 18 – Apr 1

BeansSow outdoors · Mar 11 – Mar 25

Sweet cornSow outdoors · Mar 11 – Mar 25

Cucumbers, squashSow outdoors · Mar 11 – Mar 25

Fall lettuce, spinachSow outdoors · Oct 16 – Oct 30

GarlicPlant cloves · Nov 27 – Jan 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 4) and first fall frost (Dec 11) 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 95640 came on Jan 31 — about the same time as the 1991–2020 average (Jan 31).

average
Jan 312026
Jan 31

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 Ione, CA

The soil mapped at the center of ZIP 95640 is Firebrick — gravelly sandy loam, well drained.

TextureGravelly sandy loamdrains and warms fast; dries out and needs more feeding

pH4.5strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Firebrick-Mokelumne complex, 2 to 30 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 95640; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Ione, CA

Summer high93 °Faverage high, July

Winter low39 °Faverage low, January

Hot days75days a year at 90 °F or more

Freezing nights15nights a year at 32 °F or less

Growing degree days4,486base 50 °F — the season’s usable heat

Longest day14 h 50 mindaylight on June 21

Shortest day9 h 29 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation32 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: Sutter Hill Cdf, CA (8 mi away); precipitation: Sutter Hill Cdf, CA (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

Campo Seco, CA · 8 mi

956019b

Amador City, CA · 8 mi

California planting zones →

Questions about 95640

What planting zone is ZIP code 95640?

ZIP code 95640 (Ione, 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 Ione, CA?

The median last spring frost (32 °F) near 95640 is March 4; after April 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sutter Hill Cdf station.

When is the first frost in Ione, CA?

The median first fall frost near 95640 is December 11, giving a median frost-free growing season of 285 days.

When should I plant tomatoes in 95640?

Start tomato seeds indoors around Jan 7 – Jan 21 and set transplants outside around Mar 11 – Mar 25, one to three weeks after the median last frost.

How much rain and snow does 95640 get?

About 32 inches of precipitation a year (NOAA 1991–2020 normals, Sutter Hill Cdf station).

How hot do summers get in Ione, CA?

The average high peaks at 93 °F in July, with about 75 days a year at 90 °F or more.

What kind of soil does 95640 have?

The USDA soil survey maps Firebrick at the center of ZIP 95640: gravelly sandy loam, well drained, pH about 4.5 (strongly acidic).

Did spring come early in Ione, CA in 2026?

Spring leaf-out near 95640 came on Jan 31 in 2026, about the same as the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Ione, CA?

Intermediate onions: the longest day near 95640 is 14 h 50 min, so day-neutral types bulb best; long-day varieties may not bulb fully.