S
M
T
W
T
F
S
30
72°
49°
31
73°
54°
1
73°
57°
2
74°
54°
3
70°
56°
4
75°
52°
5
79°
47°
6
76°
45°
7
88°
52°
8
94°
50°
9
99°
57°
10
90°
60°
11
73°
54°
12
79°
52°
13
79°
49°
14
82°
49°
15
71°
52°
16
70°
55°
17
73°
57°
18
78°
48°
19
75°
52°
20
66°
53°
21
67°
56°
22
69°
55°
23
83°
52°
24
81°
58°
25
80°
51°
26
74°
52°
27
74°
51°
28
78°
49°
29
78°
50°
30
82°
49°
1
81°
48°
2
82°
49°
3
85°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Napa Junction
Napa Junction's September 2026 forecast shows daily high temperatures ranging from 74° to 85°, with overnight lows between 48° and 58°. The average high for September is 80° with an average low of 51°. 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 Napa Junction. See also: October | November | December.
