S
M
T
W
T
F
S
30
82°
67°
31
91°
70°
1
97°
74°
2
95°
71°
3
92°
73°
4
92°
73°
5
84°
72°
6
79°
66°
7
82°
60°
8
85°
60°
9
79°
66°
10
76°
57°
11
82°
64°
12
86°
64°
13
74°
55°
14
71°
65°
15
89°
65°
16
71°
62°
17
77°
61°
18
71°
56°
19
69°
52°
20
72°
52°
21
72°
53°
22
75°
56°
23
76°
55°
24
73°
51°
25
72°
57°
26
77°
58°
27
77°
57°
28
76°
57°
29
75°
56°
30
75°
53°
1
72°
50°
2
67°
55°
3
73°
54°
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 67° to 89°, with overnight lows between 50° and 65°. The average high for September is 75° with an average low of 57°. 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.
