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

Planting zone for 91024 — Sierra Madre, CA

ZIP code 91024 (Sierra Madre, Los Angeles County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F. The median last spring frost is April 28 and the first fall frost November 15.

Where ZIP 91024 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 frostApr 28
First frostNov 15
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 Sierra Madre, 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 Sierra Madre, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 28median — 50% chance of a later frost
Safe for tender plantsMay 27only 10% chance of frost after
First fall frostNovember 15median — 10% chance by Oct 18
Growing season199 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 8 and returns around December 4.

From the NOAA station Mt Wilson Cbs, CA — 4 miles away, elevation 5,709 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 91024

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 17 – Mar 31
SpinachSow outdoors · Mar 17 – Apr 7
Broccoli, cabbageStart indoors · Feb 17 – Mar 3
Broccoli, cabbageTransplant · Apr 7 – Apr 21
Onion setsPlant outdoors · Mar 31 – Apr 14
PotatoesPlant outdoors · Apr 7 – Apr 21
LettuceSow outdoors · Mar 31 – Apr 14
Carrots, beetsSow outdoors · Apr 7 – Apr 21
TomatoesStart indoors · Mar 3 – Mar 17
TomatoesTransplant · May 5 – May 19
Peppers, eggplantStart indoors · Feb 17 – Mar 3
Peppers, eggplantTransplant · May 12 – May 26
BeansSow outdoors · May 5 – May 19
Sweet cornSow outdoors · May 5 – May 19
Cucumbers, squashSow outdoors · May 5 – May 19
Fall lettuce, spinachSow outdoors · Sep 20 – Oct 4
GarlicPlant cloves · Nov 1 – Dec 6
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Nov 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 91024 came on Jan 17 — 4 days earlier than the 1991–2020 average (Jan 21).

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 Sierra Madre, CA

The soil mapped at the center of ZIP 91024 is Trigo family — loam, somewhat excessively drained.

TextureLoama 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 family, granitic substratum, 60 to 90 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 91024; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sierra Madre, CA

Summer high85 °Faverage high, July
Winter low37 °Faverage low, February
Hot days16days a year at 90 °F or more
Freezing nights50nights a year at 32 °F or less
Growing degree days3,992base 50 °F — the season’s usable heat
Longest day14 h 26 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
Precipitation19.4 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 56 °F, low 38 °F 56°38° JanFebruary: average high 55 °F, low 37 °F 55°37° FebMarch: average high 59 °F, low 39 °F 59°39° MarApril: average high 63 °F, low 42 °F 63°42° AprMay: average high 70 °F, low 48 °F 70°48° MayJune: average high 79 °F, low 58 °F 79°58° JunJuly: average high 85 °F, low 64 °F 85°64° JulAugust: average high 85 °F, low 64 °F 85°64° AugSeptember: average high 81 °F, low 59 °F 81°59° SepOctober: average high 72 °F, low 51 °F 72°51° OctNovember: average high 63 °F, low 43 °F 63°43° NovDecember: average high 55 °F, low 37 °F 55°37° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 4.24 in precipitation 4.2 JanFebruary: 5.40 in precipitation 5.4 FebMarch: 2.93 in precipitation 2.9 MarApril: 1.05 in precipitation 1.1 AprMay: 0.59 in precipitation 0.6 MayJune: 0.18 in precipitation 0.2 JunJuly: 0.06 in precipitation 0.1 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.18 in precipitation 0.2 SepOctober: 0.81 in precipitation 0.8 OctNovember: 1.09 in precipitation 1.1 NovDecember: 2.82 in precipitation 2.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mt Wilson Cbs, CA (4 mi away); precipitation: Pasadena 1.8 E, CA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10a.

9102510a
Sierra Madre, CA · 1 mi
9106610a
Arcadia, CA · 3 mi
9107710a
Arcadia, CA · 3 mi
9110710a
Pasadena, CA · 3 mi
9100610a
Arcadia, CA · 3 mi
9101610a
Monrovia, CA · 3 mi
9100710a
Arcadia, CA · 3 mi
9101710a
Monrovia, CA · 3 mi

All 2 ZIP codes in Sierra Madre → · California planting zones →

Questions about 91024

What planting zone is ZIP code 91024?

ZIP code 91024 (Sierra Madre, 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).

When is the last frost in Sierra Madre, CA?

The median last spring frost (32 °F) near 91024 is April 28; after May 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mt Wilson Cbs station.

When is the first frost in Sierra Madre, CA?

The median first fall frost near 91024 is November 15, giving a median frost-free growing season of 199 days.

When should I plant tomatoes in 91024?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 91024 get?

About 19.4 inches of precipitation a year (NOAA 1991–2020 normals, Pasadena 1.8 E station).

How hot do summers get in Sierra Madre, CA?

The average high peaks at 85 °F in July, with about 16 days a year at 90 °F or more.

What kind of soil does 91024 have?

The USDA soil survey maps Trigo family at the center of ZIP 91024: loam, somewhat excessively drained, pH about 6.7 (neutral).

Did spring come early in Sierra Madre, CA in 2026?

Spring leaf-out near 91024 came on Jan 17 in 2026, 4 days earlier than the 1991–2020 average (Jan 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sierra Madre, CA?

Intermediate onions: the longest day near 91024 is 14 h 26 min, so day-neutral types bulb best; long-day varieties may not bulb fully.