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

Planting zone for Cupertino, CA

Cupertino, CA is in USDA zone 9b across its 2 ZIP codes. The median last spring frost is March 21 and the first fall frost December 15.

Cupertino on the zone map

Outlined: its 1 ZIP code areas · 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
ZIP codes2
Last frostMar 21
First frostDec 15
Growing season275 days

9b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Cupertino, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 21median — 50% chance of a later frost
Safe for tender plantsApril 28only 10% chance of frost after
First fall frostDecember 15median — 10% chance by Nov 21
Growing season275 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 29 and returns around January 4.

From the NOAA station Skyline Ridge Preserve, CA, elevation 2,270 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 Cupertino

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 7 – Feb 21
SpinachSow outdoors · Feb 7 – Feb 28
Broccoli, cabbageStart indoors · Jan 10 – Jan 24
Broccoli, cabbageTransplant · Feb 28 – Mar 14
Onion setsPlant outdoors · Feb 21 – Mar 7
PotatoesPlant outdoors · Feb 28 – Mar 14
LettuceSow outdoors · Feb 21 – Mar 7
Carrots, beetsSow outdoors · Feb 28 – Mar 14
TomatoesStart indoors · Jan 24 – Feb 7
TomatoesTransplant · Mar 28 – Apr 11
Peppers, eggplantStart indoors · Jan 10 – Jan 24
Peppers, eggplantTransplant · Apr 4 – Apr 18
BeansSow outdoors · Mar 28 – Apr 11
Sweet cornSow outdoors · Mar 28 – Apr 11
Cucumbers, squashSow outdoors · Mar 28 – Apr 11
Fall lettuce, spinachSow outdoors · Oct 20 – Nov 3
GarlicPlant cloves · Dec 1 – Jan 5
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 21) and first fall frost (Dec 15) 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 95015 came on Jan 27 — about the same time as the 1991–2020 average (Jan 28).

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 Cupertino, CA

The soil mapped at the center of ZIP 95015 is Flaskan — sandy loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH6.4slightly 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: Urban land-Flaskan complex, 0 to 2 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 95015; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cupertino, CA

Summer high78 °Faverage high, September
Winter low42 °Faverage low, January
Hot days9days a year at 90 °F or more
Freezing nights2nights a year at 32 °F or less
Growing degree days3,761base 50 °F — the season’s usable heat
Longest day14 h 44 mindaylight on June 21
Shortest day9 h 35 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation17.8 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 59 °F, low 42 °F 59°42° JanFebruary: average high 62 °F, low 45 °F 62°45° FebMarch: average high 65 °F, low 47 °F 65°47° MarApril: average high 68 °F, low 49 °F 68°49° AprMay: average high 72 °F, low 53 °F 72°53° MayJune: average high 76 °F, low 56 °F 76°56° JunJuly: average high 77 °F, low 59 °F 77°59° JulAugust: average high 77 °F, low 59 °F 77°59° AugSeptember: average high 78 °F, low 57 °F 78°57° SepOctober: average high 74 °F, low 53 °F 74°53° OctNovember: average high 66 °F, low 46 °F 66°46° NovDecember: average high 59 °F, low 42 °F 59°42° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.46 in precipitation 3.5 JanFebruary: 3.92 in precipitation 3.9 FebMarch: 2.40 in precipitation 2.4 MarApril: 1.19 in precipitation 1.2 AprMay: 0.39 in precipitation 0.4 MayJune: 0.18 in precipitation 0.2 JunJuly: 0.01 in precipitation 0.0 JulAugust: 0.12 in precipitation 0.1 AugSeptember: 0.09 in precipitation 0.1 SepOctober: 0.94 in precipitation 0.9 OctNovember: 1.57 in precipitation 1.6 NovDecember: 3.51 in precipitation 3.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Moffett Federal Airfield, CA (6 mi away); precipitation: Sunnyvale 3.6 S, CA (2 mi away). Daylight is calculated from latitude.

ZIP codes in Cupertino

950149b
25 to 30 °F
950159b
25 to 30 °F

California planting zones →

Questions about Cupertino

What planting zone is Cupertino, CA?

Cupertino, CA is in USDA hardiness zone 9b on the 2023 map (9b: 25 to 30 °F).

When is the last frost in Cupertino, CA?

The median last spring frost is March 21 and the median first fall frost is December 15 (NOAA 1991–2020 normals, Skyline Ridge Preserve station).

When can I plant a garden in Cupertino, CA?

Cool-season crops like peas and spinach go in around Feb 7 – Feb 28; tomatoes, peppers, beans and squash after about Mar 28, once frost risk has passed.

What kind of onions grow in Cupertino, CA?

Intermediate onions: the longest day is 14 h 44 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Cupertino, CA get?

About 17.8 inches of precipitation a year (NOAA 1991–2020 normals).