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
79°F
Sunny
Sunny, with a high near 79. Southwest wind 5 to 10 mph.
7-day forecast for Diamond Bar
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 79°F | Sunny | 5 to 10 mph SW | 0% |
| Tonight | 58°F | Mostly Clear | 5 to 10 mph SSW | 0% |
| Saturday | 82°F | Sunny | 5 to 10 mph SSW | 0% |
| Saturday Night | 60°F | Patchy Fog | 5 to 10 mph SW | 0% |
| Sunday | 80°F | Patchy Fog then Partly Sunny | 5 to 10 mph SW | 0% |
| Sunday Night | 60°F | Mostly Cloudy | 5 mph SSW | 1% |
| Monday | 77°F | Mostly Sunny | 5 to 10 mph SSW | 1% |
| Monday Night | 61°F | Mostly Clear | 0 to 10 mph SW | 1% |
| Tuesday | 81°F | Sunny | 0 to 10 mph SW | 0% |
| Tuesday Night | 62°F | Mostly Clear | 0 to 10 mph WNW | 0% |
| Wednesday | 88°F | Sunny | 0 to 10 mph WSW | 0% |
| Wednesday Night | 65°F | Mostly Clear | 0 to 10 mph W | 3% |
| Thursday | 89°F | Sunny | 0 to 10 mph WSW | 2% |
| Thursday Night | 66°F | Mostly Clear | 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 Sep 18, 2026.