Diamond Bar, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Diamond Bar, a city in Los Angeles County, California.
Overnight
64°F
Partly Cloudy
Partly cloudy, with a low around 64. Southwest wind around 0 mph.
7-day forecast for Diamond Bar
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 64°F | Partly Cloudy | 0 mph | 0% |
| Tuesday | 90°F | Sunny | 0 to 10 mph SW | 0% |
| Tuesday Night | 63°F | Mostly Clear | 0 to 10 mph SW | 0% |
| Wednesday | 89°F | Sunny | 0 to 10 mph SW | 0% |
| Wednesday Night | 64°F | Mostly Clear | 0 to 10 mph SW | 0% |
| Thursday | 89°F | Sunny | 0 to 10 mph SW | 1% |
| Thursday Night | 65°F | Mostly Clear | 0 to 10 mph SW | 1% |
| Friday | 89°F | Sunny | 0 to 10 mph SW | 0% |
| Friday Night | 66°F | Mostly Clear | 0 to 10 mph WSW | 0% |
| Saturday | 92°F | Sunny | 0 to 10 mph WSW | 0% |
| Saturday Night | 66°F | Mostly Clear | 0 to 10 mph SW | 0% |
| Sunday | 91°F | Sunny | 0 to 10 mph SW | 0% |
| Sunday Night | 65°F | Mostly Clear | 0 to 10 mph SW | 1% |
| Monday | 88°F | Sunny | 0 to 10 mph SW | 1% |
Forecast source: National Weather Service (api.weather.gov) for Diamond Bar (34.002, -117.818). Updated through the day.
Growing snapshot for Diamond Bar
Last spring frost
Jan 8
First fall frost
Dec 28
Growing season
354 days
Hardiness zone
10a
More local growing data for Diamond Bar: nearby ZIP 91765 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, Pomona/Fairplex, Ca (7.2 mi from Diamond Bar). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.