Deconstruct SunPasadena, CA: Hardiness Zone 10b & Sunlight by Season
Pasadena is in USDA hardiness zone 10b. Here’s what that means for winter, plus sunrise, sunset, daylight hours and the sun’s path through the year.
Zone 10b in Pasadena
On the 2023 USDA Plant Hardiness Zone Map, Pasadena falls in zone 10b. That means the coldest night of a typical winter drops to between 35 and 40 °F. Perennials, shrubs and trees labeled for zone 10b or colder (a lower number) should survive the winter here. Parts of the area sit near the boundary with zone 10a, so a sheltered courtyard or an exposed hilltop can behave like the neighboring zone.
A zone only covers winter cold. For a plant to do well it also needs the right amount of sun, and that varies far more from one corner of a yard to the next than the zone does across town.
This is not the official USDA Plant Hardiness Zone Map. Zones are derived from the official 2023 dataset, resampled to about 2 km.
Nearby cities
- Glendale, CA Zone 10a
- Los Angeles, CA Zone 10b
- Fullerton, CA Zone 10a
- Torrance, CA Zone 10b
- Long Beach, CA Zone 10b
- Santa Clarita, CA Zone 10a
- Garden Grove, CA Zone 10b
- Palmdale, CA Zone 9a
The sun over Pasadena
On the June solstice the sun rises in the northeast at 5:41 AM and climbs to 79° above the horizon at 12:54 PM. On the December solstice the noon sun reaches only 32°, so a 20-foot tree casts a noon shadow about 32 feet long. In June the same tree’s noon shadow is only 4 feet.
Sunrise, sunset & daylight by month
| Date | Sunrise | Sunset | Daylight | Noon sun |
|---|---|---|---|---|
| Jan 21 | 6:56 AM | 5:12 PM | 10h 16m | 36° |
| Feb 21 | 6:30 AM | 5:42 PM | 11h 11m | 46° |
| Mar 21 | 6:54 AM | 7:05 PM | 12h 11m | 56° |
| Apr 21 | 6:13 AM | 7:28 PM | 13h 15m | 68° |
| May 21 | 5:46 AM | 7:52 PM | 14h 05m | 76° |
| Jun 21 | 5:41 AM | 8:07 PM | 14h 26m | 79° |
| Jul 21 | 5:56 AM | 8:01 PM | 14h 05m | 76° |
| Aug 21 | 6:18 AM | 7:32 PM | 13h 14m | 68° |
| Sep 21 | 6:40 AM | 6:50 PM | 12h 10m | 56° |
| Oct 21 | 7:02 AM | 6:10 PM | 11h 08m | 45° |
| Nov 21 | 6:31 AM | 4:45 PM | 10h 14m | 36° |
| Dec 21 | 6:54 AM | 4:47 PM | 9h 52m | 32° |
Local time (Los Angeles), including daylight saving time. “Noon sun” is the sun’s height above the horizon at solar noon.
Daylight through the year
What “full sun” means in Pasadena
Full sun is 6+ hours of direct sun. In Pasadena an open spot has 14.4 hours of daylight to work with in June and 9.9 in December, so a bed that clears 6 hours in summer can easily drop to part shade in winter once the low sun slips behind trees and houses.
Measure the sun in your Pasadena yard
Daylight is the ceiling. Deconstruct Sun traces the trees and buildings around one exact spot and tells you its real direct-sun hours, today and at every solstice and equinox.
Questions
What hardiness zone is Pasadena, CA in?
Pasadena, California is in USDA plant hardiness zone 10b on the 2023 map. The average coldest winter night is 35 to 40 °F (1.7 to 4.4 °C). It is near the boundary with zone 10a.
How many hours of daylight does Pasadena get?
About 14.4 hours on the June solstice (sunrise 5:41 AM, sunset 8:07 PM) and 9.9 hours on the December solstice (sunrise 6:54 AM, sunset 4:47 PM). Around the equinoxes it is close to 12 hours.
How many hours of sun does my Pasadena yard get?
Up to the daylight hours above, minus whatever trees, buildings and fences block. In winter, when the sun stays low, that can be most of it. The Deconstruct Sun iPhone app measures the real direct-sun hours for one exact spot by having you trace what is around it.
When is the best time to plant in Pasadena?
Zone 10b tells you which perennials survive winter, not planting dates. For timing, use your local average frost dates from your county extension office, and choose plants rated for zone 10b or colder.
Source: USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture, planthardiness.ars.usda.gov. Underlying data © PRISM Group, Oregon State University, prism.oregonstate.edu, accessed 2026-08-30. Sun times calculated for 34.161, -118.138.