Diamond Bar (CA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Diamond Bar.
Climate overview of Diamond Bar
Temperatures in Diamond Bar, California, United States of America, vary greatly throughout the year. August is the hottest month at 33°C (91°F), while December is the coldest at 19°C (66°F).
The city tends toward dry conditions, with around 312 mm (12 in) of rainfall per year. It does, however, have a distinct dry season from April to November, with very warm summers and pleasant winters. Sunshine peaks in July, when the city sees around 12.3 hours of sunshine per day.
Diamond Bar Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Diamond Bar - and find the best time to visit.
Monthly Temperature in Diamond Bar
The climate in Diamond Bar is known for significant temperature differences throughout the year, making the weather dynamic. Typically, average maximum daytime temperatures range from a very warm 33°C (91°F) in August to a pleasant 19°C (66°F) in the coolest month, December.
Nights vary from 17°C (63°F) in August to around 7°C (45°F) during the colder months.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Diamond Bar
Diamond Bar maintains relatively dry conditions year-round, recording average annual precipitation of 312 mm (12 in). The climate in Diamond Bar shows significant variation throughout the year. Expect moderate rainfall in December, the wettest month, with an average of 84 mm (3.3 in) of precipitation over 9 rainy days.
In contrast, the driest month June offers drier and sunnier days, with around 0.2 mm (0.01 in) of rainfall over 0 rainy days. For more details, please visit our Diamond Bar Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Diamond Bar
For those who appreciate different seasons, Diamond Bar serves as an ideal destination. Expect longer, more sun-filled days in July with an average of 12.3 hours of sunshine daily, and embrace the darker days in January, offering only 6.6 hours of daily sunlight.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Best Time to Visit Diamond Bar
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: January, February, March, April, May, October and November
- Warmest weather: July, August and September
- Most sunshine: July and August
- Fewer rainy days: May, June, July, August and September
- Seasonal pattern: A distinct dry season from April to November, with very warm summers and pleasant winters
Frequently asked questions about the climate in Diamond Bar
What is the best time to visit Diamond Bar?
January, February, March, April, May, October and November typically offer the most optimal weather in Diamond Bar. In contrast, July and August tend to have less optimal conditions. Diamond Bar has a distinct dry season from April to November, with very warm summers and pleasant winters.
What temperatures can I expect in Diamond Bar?
Daytime highs range from 19°C (66°F) in December to 33°C (91°F) in August. Nighttime lows range from 7°C (45°F) to 17°C (63°F). Temperatures vary considerably through the year.
How much rain does Diamond Bar get?
Annual rainfall is around 312 mm (12 in). December is the wettest month with 84 mm (3.3 in), while June is the driest with 0.2 mm (0.01 in).
How sunny is Diamond Bar?
Diamond Bar receives around 3,279 hours of sunshine per year. July is the sunniest month with 369 hours, while January is the cloudiest with just 198 hours. Overall, Diamond Bar enjoys abundant sunshine.
Diamond Bar 3-Day Forecast
Diamond Bar on the map
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