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Current
Hourly
7 Days
14 Days
Weekend
Monthly
Precipitation
Temperature
Wind
Temperature Unit Selection
°Celsius
°Fahrenheit
Monthly Historical Averages
Diamond Bar, CA
Content continues below
September
Average Temperature
High
30°
Feels 30
Low
17°
Feels 16
Average Precipitation
1 Days
Rain amount
3.8mm
Snow amount
0cm
Content continues below
Daily Historical Averages
September 2026
S
M
T
W
T
F
S
1
2
3
4
5
6
7
8
9
10
11
12
13
14
31°
15
29°
16
27°
17
28°
18
29°
19
30°
20
28°
21
28°
22
27°
23
25°
24
25°
25
28°
26
30°
27
32°
28
31°
29
30
Forecast
Monday, September 14, 2026
Day
31°
Feels 31
Wind
15 km/h SW
Gust
23 km/h
Humidity
37%
P.O.P
10%
Night
18°
Feels 18
Wind
13 km/h SW
Gust
20 km/h
Humidity
90%
P.O.P
10%
Historical Averages
Sep 14
High
Feels
Low
Feels
Precip Frequency
Total Daylight
Humidity
Historical Averages are based on data recorded from 2000 onwards.