Deconstruct SunHilo, HI: Hardiness Zone 12b & Sunlight by Season
Hilo is in USDA hardiness zone 12b. Here’s what that means for winter, plus sunrise, sunset, daylight hours and the sun’s path through the year.
Zone 12b in Hilo
On the 2023 USDA Plant Hardiness Zone Map, Hilo falls in zone 12b. That means the coldest night of a typical winter drops to between 55 and 60 °F. Perennials, shrubs and trees labeled for zone 12b or colder (a lower number) should survive the winter here.
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
- Kihei, HI Zone 12b
- Kahului, HI Zone 12b
- Honolulu, HI Zone 12b
- Lihue, HI Zone 12b
- Santa Cruz, CA Zone 10a
- San Francisco, CA Zone 10b
- Santa Rosa, CA Zone 9b
- Berkeley, CA Zone 10a
The sun over Hilo
On the June solstice the sun rises in the northeast at 5:42 AM and climbs to 86° above the horizon at 12:22 PM. On the December solstice the noon sun reaches only 47°, so a 20-foot tree casts a noon shadow about 19 feet long. In June the same tree’s noon shadow is only 1 feet.
Sunrise, sunset & daylight by month
| Date | Sunrise | Sunset | Daylight | Noon sun |
|---|---|---|---|---|
| Jan 21 | 6:57 AM | 6:06 PM | 11h 09m | 51° |
| Feb 21 | 6:45 AM | 6:22 PM | 11h 37m | 60° |
| Mar 21 | 6:23 AM | 6:31 PM | 12h 08m | 71° |
| Apr 21 | 5:57 AM | 6:40 PM | 12h 42m | 82° |
| May 21 | 5:42 AM | 6:51 PM | 13h 09m | 89° |
| Jun 21 | 5:42 AM | 7:01 PM | 13h 19m | 86° |
| Jul 21 | 5:52 AM | 7:01 PM | 13h 09m | 89° |
| Aug 21 | 6:02 AM | 6:44 PM | 12h 42m | 82° |
| Sep 21 | 6:09 AM | 6:17 PM | 12h 08m | 71° |
| Oct 21 | 6:17 AM | 5:52 PM | 11h 35m | 59° |
| Nov 21 | 6:32 AM | 5:40 PM | 11h 08m | 50° |
| Dec 21 | 6:50 AM | 5:46 PM | 10h 57m | 47° |
Local time (Honolulu), 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 Hilo
Full sun is 6+ hours of direct sun. In Hilo an open spot has 13.3 hours of daylight to work with in June and 10.9 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 Hilo 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 Hilo, HI in?
Hilo, Hawaii is in USDA plant hardiness zone 12b on the 2023 map. The average coldest winter night is 55 to 60 °F (12.8 to 15.6 °C).
How many hours of daylight does Hilo get?
About 13.3 hours on the June solstice (sunrise 5:42 AM, sunset 7:01 PM) and 10.9 hours on the December solstice (sunrise 6:50 AM, sunset 5:46 PM). Around the equinoxes it is close to 12 hours.
How many hours of sun does my Hilo 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 Hilo?
Zone 12b 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 12b 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 19.689, -155.083.