S
M
T
W
T
F
S
30
77°
67°
31
77°
63°
1
72°
58°
2
71°
58°
3
73°
59°
4
73°
58°
5
74°
60°
6
68°
54°
7
75°
60°
8
76°
60°
9
76°
59°
10
70°
59°
11
72°
58°
12
75°
58°
13
69°
56°
14
70°
57°
15
71°
58°
16
74°
57°
17
74°
57°
18
73°
53°
19
62°
49°
20
63°
54°
21
68°
54°
22
66°
55°
23
67°
50°
24
61°
48°
25
60°
46°
26
59°
46°
27
59°
48°
28
60°
49°
29
62°
49°
30
63°
52°
1
66°
45°
2
57°
44°
3
56°
49°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Markham
Markham's September 2026 forecast shows daily high temperatures ranging from 56° to 77°, with overnight lows between 44° and 67°. The average high for September is 68° with an average low of 54°. 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 Markham. See also: October | November | December.
