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

Planting zone for 91709 — Chino Hills, CA

ZIP code 91709 (Chino Hills, San Bernardino County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 91709 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.

Zone10a30 to 35 °F
Coldest night−1.1 to 1.7 °C
Last frostrare
First frostrare
2012 zone10a

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 10a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Chino Hills, 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

A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station Chino Airport, CA — 6 miles away, elevation 650 ft) the median growing season is 335 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.

Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.

When spring arrived in 2026

In 2026, spring leaf-out near 91709 came on Jan 16 — 6 days earlier than the 1991–2020 average (Jan 22).

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 Chino Hills, CA

The soil mapped at the center of ZIP 91709 is Alo — clay, well drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH7.3neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Alo clay, 30 to 50 percent slopes, warm MAAT, MLRA 20.

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 91709; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Chino Hills, CA

Summer high96 °Faverage high, August
Winter low40 °Faverage low, December
Hot days99days a year at 90 °F or more
Freezing nights11nights a year at 32 °F or less
Growing degree days5,949base 50 °F — the season’s usable heat
Longest day14 h 25 mindaylight on June 21
Shortest day9 h 53 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation10 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 70 °F, low 42 °F 70°42° JanFebruary: average high 70 °F, low 43 °F 70°43° FebMarch: average high 73 °F, low 46 °F 73°46° MarApril: average high 77 °F, low 49 °F 77°49° AprMay: average high 81 °F, low 54 °F 81°54° MayJune: average high 88 °F, low 59 °F 88°59° JunJuly: average high 94 °F, low 63 °F 94°63° JulAugust: average high 96 °F, low 63 °F 96°63° AugSeptember: average high 93 °F, low 60 °F 93°60° SepOctober: average high 85 °F, low 53 °F 85°53° OctNovember: average high 76 °F, low 45 °F 76°45° NovDecember: average high 69 °F, low 40 °F 69°40° Dec

Precipitation by month inches

0″1″2″3″January: 2.17 in precipitation 2.2 JanFebruary: 2.68 in precipitation 2.7 FebMarch: 1.43 in precipitation 1.4 MarApril: 0.55 in precipitation 0.6 AprMay: 0.17 in precipitation 0.2 MayJune: 0.02 in precipitation 0.0 JunJuly: 0.08 in precipitation 0.1 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.06 in precipitation 0.1 SepOctober: 0.53 in precipitation 0.5 OctNovember: 0.59 in precipitation 0.6 NovDecember: 1.69 in precipitation 1.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Chino Airport, CA (6 mi away); precipitation: Chino Airport, 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.

9288710a
Yorba Linda, CA · 4 mi
9282310a
Brea, CA · 4 mi
9171010a
Chino, CA · 5 mi
917089b
Chino, CA · 5 mi
9288610a
Yorba Linda, CA · 5 mi
9176510a
Diamond Bar, CA · 6 mi
9280810a
Anaheim, CA · 6 mi
9288510a
Yorba Linda, CA · 7 mi

California planting zones →

Questions about 91709

What planting zone is ZIP code 91709?

ZIP code 91709 (Chino Hills, CA) is in USDA hardiness zone 10a on the 2023 map: the coldest night of an average winter reaches 30 to 35 °F (−1.1 to 1.7 °C).

How much rain and snow does 91709 get?

About 10 inches of precipitation a year (NOAA 1991–2020 normals, Chino Airport station).

How hot do summers get in Chino Hills, CA?

The average high peaks at 96 °F in August, with about 99 days a year at 90 °F or more.

What kind of soil does 91709 have?

The USDA soil survey maps Alo at the center of ZIP 91709: clay, well drained, pH about 7.3 (neutral).

Did spring come early in Chino Hills, CA in 2026?

Spring leaf-out near 91709 came on Jan 16 in 2026, 6 days earlier than the 1991–2020 average (Jan 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Chino Hills, CA?

Intermediate onions: the longest day near 91709 is 14 h 25 min, so day-neutral types bulb best; long-day varieties may not bulb fully.