S
M
T
W
T
F
S
30
95°
72°
31
94°
72°
1
93°
75°
2
95°
80°
3
94°
78°
4
91°
78°
5
92°
74°
6
90°
76°
7
96°
74°
8
95°
75°
9
90°
74°
10
92°
74°
11
93°
75°
12
92°
75°
13
92°
74°
14
91°
75°
15
89°
72°
16
88°
71°
17
88°
70°
18
87°
71°
19
88°
69°
20
86°
69°
21
88°
68°
22
88°
70°
23
86°
71°
24
86°
71°
25
85°
70°
26
86°
70°
27
86°
69°
28
85°
70°
29
86°
70°
30
84°
66°
1
81°
61°
2
79°
62°
3
80°
61°
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 79° to 95°, with overnight lows between 61° and 75°. The average high for September is 87° with an average low of 70°. 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.
