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

Planting zone for 95221 — Altaville, CA

ZIP code 95221 (Altaville, Calaveras County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 20 and the first fall frost December 11.

Where ZIP 95221 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 frostFeb 20
First frostDec 11
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 Altaville, 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 Altaville, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 20median — 50% chance of a later frost
Safe for tender plantsApril 7only 10% chance of frost after
First fall frostDecember 11median — 10% chance by Nov 24
Growing season290 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 6 and returns around December 24.

From the NOAA station New Melones Dam Hq, CA — 6 miles away, elevation 961 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 95221

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 9 – Jan 23
SpinachSow outdoors · Jan 9 – Jan 30
Broccoli, cabbageStart indoors · Dec 12 – Dec 26
Broccoli, cabbageTransplant · Jan 30 – Feb 13
Onion setsPlant outdoors · Jan 23 – Feb 6
PotatoesPlant outdoors · Jan 30 – Feb 13
LettuceSow outdoors · Jan 23 – Feb 6
Carrots, beetsSow outdoors · Jan 30 – Feb 13
TomatoesStart indoors · Dec 26 – Jan 9
TomatoesTransplant · Feb 27 – Mar 13
Peppers, eggplantStart indoors · Dec 12 – Dec 26
Peppers, eggplantTransplant · Mar 6 – Mar 20
BeansSow outdoors · Feb 27 – Mar 13
Sweet cornSow outdoors · Feb 27 – Mar 13
Cucumbers, squashSow outdoors · Feb 27 – Mar 13
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 (Feb 20) 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 95221 came on Jan 28 — 6 days earlier than the 1991–2020 average (Feb 3).

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 Altaville, CA

The soil mapped at the center of ZIP 95221 is Loafercreek — gravelly loam, well drained.

TextureGravelly loama good balance for most vegetables
pH6.0slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Loafercreek-Bonanza complex, 3 to 15 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 95221; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Altaville, CA

Summer high97 °Faverage high, July
Winter low38 °Faverage low, January
Hot days98days a year at 90 °F or more
Freezing nights13nights a year at 32 °F or less
Growing degree days5,108base 50 °F — the season’s usable heat
Longest day14 h 49 mindaylight on June 21
Shortest day9 h 31 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation29.8 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 57 °F, low 38 °F 57°38° JanFebruary: average high 61 °F, low 40 °F 61°40° FebMarch: average high 65 °F, low 44 °F 65°44° MarApril: average high 70 °F, low 46 °F 70°46° AprMay: average high 79 °F, low 52 °F 79°52° MayJune: average high 89 °F, low 59 °F 89°59° JunJuly: average high 97 °F, low 65 °F 97°65° JulAugust: average high 96 °F, low 65 °F 96°65° AugSeptember: average high 91 °F, low 60 °F 91°60° SepOctober: average high 80 °F, low 52 °F 80°52° OctNovember: average high 66 °F, low 44 °F 66°44° NovDecember: average high 57 °F, low 38 °F 57°38° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 5.85 in precipitation 5.8 JanFebruary: 4.85 in precipitation 4.8 FebMarch: 4.77 in precipitation, 0.2 in snowfall 4.8 MarApril: 2.58 in precipitation 2.6 AprMay: 1.48 in precipitation 1.5 MayJune: 0.36 in precipitation 0.4 JunJuly: 0.03 in precipitation 0.0 JulAugust: 0.04 in precipitation 0.0 AugSeptember: 0.21 in precipitation 0.2 SepOctober: 1.51 in precipitation 1.5 OctNovember: 2.91 in precipitation 2.9 NovDecember: 5.16 in precipitation 5.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: New Melones Dam Hq, CA (6 mi away); precipitation: New Melones Dam Hq, CA (6 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.

952229a
Angels Camp, CA · 3 mi
952519a
Vallecito, CA · 5 mi
952299a
Douglas Flat, CA · 6 mi
952479a
Murphys, CA · 7 mi
952499a
San Andreas, CA · 9 mi
953109a
Columbia, CA · 9 mi
953709a
Sonora, CA · 12 mi
952338b
Hathaway Pines, CA · 13 mi

California planting zones →

Questions about 95221

What planting zone is ZIP code 95221?

ZIP code 95221 (Altaville, 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 Altaville, CA?

The median last spring frost (32 °F) near 95221 is February 20; after April 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, New Melones Dam Hq station.

When is the first frost in Altaville, CA?

The median first fall frost near 95221 is December 11, giving a median frost-free growing season of 290 days.

When should I plant tomatoes in 95221?

Start tomato seeds indoors around Dec 26 – Jan 9 and set transplants outside around Feb 27 – Mar 13, one to three weeks after the median last frost.

How much rain and snow does 95221 get?

About 29.8 inches of precipitation a year (NOAA 1991–2020 normals, New Melones Dam Hq station).

How hot do summers get in Altaville, CA?

The average high peaks at 97 °F in July, with about 98 days a year at 90 °F or more.

What kind of soil does 95221 have?

The USDA soil survey maps Loafercreek at the center of ZIP 95221: gravelly loam, well drained, pH about 6.0 (slightly acidic).

Did spring come early in Altaville, CA in 2026?

Spring leaf-out near 95221 came on Jan 28 in 2026, 6 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Altaville, CA?

Intermediate onions: the longest day near 95221 is 14 h 49 min, so day-neutral types bulb best; long-day varieties may not bulb fully.