S
M
T
W
T
F
S
30
74°
51°
31
73°
47°
1
67°
49°
2
67°
48°
3
66°
47°
4
66°
47°
5
67°
48°
6
67°
47°
7
70°
52°
8
72°
53°
9
66°
46°
10
67°
50°
11
69°
52°
12
70°
50°
13
69°
51°
14
71°
49°
15
67°
45°
16
64°
45°
17
62°
44°
18
65°
50°
19
62°
45°
20
71°
49°
21
63°
47°
22
Hist. Avg.
64°
46°
23
Hist. Avg.
64°
46°
24
Hist. Avg.
63°
45°
25
Hist. Avg.
63°
45°
26
Hist. Avg.
63°
44°
27
Hist. Avg.
62°
44°
28
Hist. Avg.
62°
44°
29
Hist. Avg.
61°
43°
30
Hist. Avg.
61°
43°
1
Hist. Avg.
61°
43°
2
Hist. Avg.
60°
42°
3
Hist. Avg.
60°
42°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Old Ottawa
Old Ottawa's September 2026 forecast shows daily high temperatures ranging from 62° to 74°, with overnight lows between 44° and 53°. The average high for September is 68° with an average low of 48°. 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 Old Ottawa. See also: October | November | December.
