Weather in Diamond Bar in September
Diamond Bar, United States averages a high of 30.4°C (86.7°F) and low of 17.4°C (63.3°F) in September, with 1 rain days and 11.5 hours of daily sunshine. Travel score: 98.6/100 (Excellent). The best time to visit Diamond Bar is July.
High
30°C87°F
Low
17°C63°F
🌧️
1
rain days
☀️
11.5
hrs/day sunshine
💧
60%
humidity
99— Excellent
September in Diamond Bar is hot and dry — excellent conditions for exploring.
What are the average temperatures in Diamond Bar?
How much does it rain in Diamond Bar in September?
Diamond Bar receives an average of 8.2mm of rainfall across 1 rainy days in September. The annual total is 393.2mm.
What should I pack for Diamond Bar in September?
Essentials
👟
Comfortable walking shoes
Essential for exploring the city
👕
Light, breathable clothing
Hot weather with highs around 30°C
🧢
Sun hat or cap
Protection from intense sun
🧴
Sunscreen SPF 30+
12 hours of sunshine daily
🕶️
Sunglasses
Protect your eyes from bright sun
Recommended
🧥
Evening jacket or cardigan
Temperature drops 13°C from day to night
Traveling to United States in September?
Don't let a public holiday surprise you — restaurants, shops, and attractions may be closed.
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Data based on 1994–2024 averages · Last updated: 2024-12-31