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.
This Afternoon
72°F
Mostly Sunny
Mostly sunny, with a high near 72. Southwest wind 5 to 10 mph.
7-day forecast for Diamond Bar
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 72°F | Mostly Sunny | 5 to 10 mph SW | 0% |
| Tonight | 53°F | Mostly Clear | 0 to 10 mph W | 0% |
| Wednesday | 73°F | Sunny | 0 to 5 mph SSW | 0% |
| Wednesday Night | 55°F | Mostly Clear | 5 to 10 mph W | 0% |
| Thursday | 77°F | Sunny | 0 to 10 mph NNE | 0% |
| Thursday Night | 56°F | Mostly Clear | 0 to 10 mph N | 0% |
| Friday | 80°F | Sunny | 0 to 10 mph NE | 0% |
| Friday Night | 57°F | Clear | 0 to 15 mph NNE | 0% |
| Saturday | 83°F | Sunny | 0 to 10 mph NE | 0% |
| Saturday Night | 60°F | Clear | 0 to 15 mph NNE | 0% |
| Sunday | 84°F | Sunny | 0 to 10 mph ENE | 0% |
| Sunday Night | 62°F | Partly Cloudy | 0 to 15 mph NNE | 0% |
| Monday | 81°F | Mostly Sunny | 0 to 5 mph ESE | 0% |
| Monday Night | 60°F | Partly Cloudy | 0 to 5 mph NE | 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 Nov 4, 2026.