S
M
T
W
T
F
S
30
90°
64°
31
93°
70°
1
93°
70°
2
97°
72°
3
98°
74°
4
96°
69°
5
89°
68°
6
88°
60°
7
87°
63°
8
85°
65°
9
89°
67°
10
90°
63°
11
84°
63°
12
83°
61°
13
84°
61°
14
83°
59°
15
81°
55°
16
77°
60°
17
78°
59°
18
74°
59°
19
82°
60°
20
76°
59°
21
77°
59°
22
79°
58°
23
77°
55°
24
73°
57°
25
80°
57°
26
79°
54°
27
74°
49°
28
70°
46°
29
69°
45°
30
70°
47°
1
69°
45°
2
71°
52°
3
72°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Irvine
Irvine's September 2026 forecast shows daily high temperatures ranging from 69° to 98°, with overnight lows between 45° and 74°. The average high for September is 81° with an average low of 59°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Irvine. See also: October | November | December.
