S
M
T
W
T
F
S
30
107°
88°
31
104°
88°
1
105°
85°
2
105°
82°
3
104°
81°
4
105°
82°
5
99°
85°
6
105°
85°
7
106°
87°
8
109°
87°
9
107°
87°
10
108°
87°
11
105°
85°
12
104°
79°
13
102°
79°
14
105°
78°
15
103°
79°
16
103°
77°
17
102°
79°
18
104°
78°
19
103°
77°
20
99°
73°
21
96°
75°
22
96°
72°
23
94°
71°
24
94°
70°
25
94°
70°
26
97°
72°
27
93°
71°
28
93°
74°
29
99°
74°
30
94°
70°
1
91°
69°
2
95°
73°
3
97°
71°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in San Luis
San Luis's September 2026 forecast shows daily high temperatures ranging from 91° to 109°, with overnight lows between 69° and 87°. The average high for September is 100° with an average low of 76°. 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 San Luis. See also: October | November | December.
