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

Planting zone for 91702 — Azusa, CA

ZIP code 91702 (Azusa, Los Angeles County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is May 16 and the first fall frost October 13.

Where ZIP 91702 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 frostMay 16
First frostOct 13
2012 zone10a

Was 10a on the 2012 map — half a zone colder 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 Azusa, 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 Azusa, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 16median — 50% chance of a later frost
Safe for tender plantsJune 9only 10% chance of frost after
First fall frostOctober 13median — 10% chance by Sep 25
Growing season151 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 25 and returns around October 30.

From the NOAA station Wrightwood, CA — 11 miles away, elevation 6,001 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 91702

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 4 – Apr 18
SpinachSow outdoors · Apr 4 – Apr 25
Broccoli, cabbageStart indoors · Mar 7 – Mar 21
Broccoli, cabbageTransplant · Apr 25 – May 9
Onion setsPlant outdoors · Apr 18 – May 2
PotatoesPlant outdoors · Apr 25 – May 9
LettuceSow outdoors · Apr 18 – May 2
Carrots, beetsSow outdoors · Apr 25 – May 9
TomatoesStart indoors · Mar 21 – Apr 4
TomatoesTransplant · May 23 – Jun 6
Peppers, eggplantStart indoors · Mar 7 – Mar 21
Peppers, eggplantTransplant · May 30 – Jun 13
BeansSow outdoors · May 23 – Jun 6
Sweet cornSow outdoors · May 23 – Jun 6
Cucumbers, squashSow outdoors · May 23 – Jun 6
Fall lettuce, spinachSow outdoors · Aug 18 – Sep 1
GarlicPlant cloves · Sep 29 – Nov 3
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Oct 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 91702 came on Feb 5 — 13 days earlier than the 1991–2020 average (Feb 18).

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 Azusa, CA

The soil mapped at the center of ZIP 91702 is Trigo family — gravelly loam, somewhat excessively drained.

TextureGravelly loama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter1%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Trigo, granitic substratum-Exchequer families-Rock outcrop complex, 60 to 100 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 91702; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Azusa, CA

Summer high83 °Faverage high, July
Winter low25 °Faverage low, February
Hot days4days a year at 90 °F or more
Freezing nights159nights a year at 32 °F or less
Growing degree days2,050base 50 °F — the season’s usable heat
Longest day14 h 27 mindaylight on June 21
Shortest day9 h 52 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation30.4 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 48 °F, low 26 °F 48°26° JanFebruary: average high 48 °F, low 25 °F 48°25° FebMarch: average high 54 °F, low 29 °F 54°29° MarApril: average high 60 °F, low 32 °F 60°32° AprMay: average high 69 °F, low 39 °F 69°39° MayJune: average high 78 °F, low 44 °F 78°44° JunJuly: average high 83 °F, low 53 °F 83°53° JulAugust: average high 82 °F, low 51 °F 82°51° AugSeptember: average high 75 °F, low 46 °F 75°46° SepOctober: average high 64 °F, low 37 °F 64°37° OctNovember: average high 55 °F, low 29 °F 55°29° NovDecember: average high 48 °F, low 25 °F 48°25° Dec

Precipitation by month inches

0″2″4″6″8″January: 7.12 in precipitation 7.1 JanFebruary: 7.51 in precipitation 7.5 FebMarch: 4.62 in precipitation 4.6 MarApril: 2.17 in precipitation 2.2 AprMay: 0.94 in precipitation 0.9 MayJune: 0.30 in precipitation 0.3 JunJuly: 0.22 in precipitation 0.2 JulAugust: 0.21 in precipitation 0.2 AugSeptember: 0.15 in precipitation 0.1 SepOctober: 0.97 in precipitation 1.0 OctNovember: 1.76 in precipitation 1.8 NovDecember: 4.48 in precipitation 4.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Wrightwood, CA (11 mi away); precipitation: Crystal Lake Fc238c, CA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

923977b
Wrightwood, CA · 6 mi
917598a
Mount Baldy, CA · 6 mi
935638a
Valyermo, CA · 6 mi
9174110a
Glendora, CA · 8 mi
9175010a
La Verne, CA · 9 mi
9174010a
Glendora, CA · 12 mi
9171110a
Claremont, CA · 12 mi
9177310a
San Dimas, CA · 12 mi

California planting zones →

Questions about 91702

What planting zone is ZIP code 91702?

ZIP code 91702 (Azusa, 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 Azusa, CA?

The median last spring frost (32 °F) near 91702 is May 16; after June 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wrightwood station.

When is the first frost in Azusa, CA?

The median first fall frost near 91702 is October 13, giving a median frost-free growing season of 151 days.

When should I plant tomatoes in 91702?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 91702 get?

About 30.4 inches of precipitation a year (NOAA 1991–2020 normals, Crystal Lake Fc238c station).

How hot do summers get in Azusa, CA?

The average high peaks at 83 °F in July, with about 4 days a year at 90 °F or more.

What kind of soil does 91702 have?

The USDA soil survey maps Trigo family at the center of ZIP 91702: gravelly loam, somewhat excessively drained, pH about 6.7 (neutral).

Did spring come early in Azusa, CA in 2026?

Spring leaf-out near 91702 came on Feb 5 in 2026, 13 days earlier than the 1991–2020 average (Feb 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Azusa, CA?

Intermediate onions: the longest day near 91702 is 14 h 27 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 91702 change?

Yes. The 2012 USDA map put 91702 in zone 10a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.