S
M
T
W
T
F
S
30
76°
57°
31
77°
58°
1
78°
58°
2
75°
52°
3
66°
49°
4
65°
47°
5
69°
45°
6
66°
45°
7
67°
54°
8
70°
57°
9
76°
56°
10
76°
50°
11
74°
45°
12
64°
48°
13
66°
47°
14
65°
55°
15
73°
55°
16
73°
54°
17
74°
55°
18
74°
55°
19
75°
52°
20
73°
42°
21
68°
43°
22
59°
41°
23
60°
41°
24
63°
51°
25
66°
49°
26
70°
41°
27
65°
39°
28
57°
38°
29
58°
40°
30
59°
40°
1
61°
43°
2
63°
48°
3
66°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Lanark
Lanark's September 2026 forecast shows daily high temperatures ranging from 57° to 78°, with overnight lows between 38° and 58°. The average high for September is 68° with an average low of 49°. 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 Lanark. See also: October | November | December.