Planting zone for 91020 — Montrose, CA
ZIP code 91020 (Montrose, Los Angeles County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.
Where ZIP 91020 is
Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoomNot 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.
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 ServiceLoading the forecast for Montrose, 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 Pasadena, CA — 7 miles away, elevation 863 ft) the median growing season is 365 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 91020 came on Jan 17 — 4 days earlier than the 1991–2020 average (Jan 21).
Jan 212026
Jan 17
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 Montrose, CA
The soil mapped at the center of ZIP 91020 is Palmview — sandy loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.
Map unit: Urban land-Palmview-Tujunga, gravelly complex, 2 to 9 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 91020; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Montrose, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Pasadena, CA (7 mi away); precipitation: Glendale 2.4 Wsw, CA (5 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.
Questions about 91020
What planting zone is ZIP code 91020?
ZIP code 91020 (Montrose, 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 91020 get?
About 16.7 inches of precipitation a year (NOAA 1991–2020 normals, Glendale 2.4 Wsw station).
How hot do summers get in Montrose, CA?
The average high peaks at 91 °F in August, with about 74 days a year at 90 °F or more.
What kind of soil does 91020 have?
The USDA soil survey maps Palmview at the center of ZIP 91020: sandy loam, well drained, pH about 6.7 (neutral).
Did spring come early in Montrose, CA in 2026?
Spring leaf-out near 91020 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 Montrose, CA?
Intermediate onions: the longest day near 91020 is 14 h 26 min, so day-neutral types bulb best; long-day varieties may not bulb fully.