S
M
T
W
T
F
S
30
70°
66°
31
76°
66°
1
78°
70°
2
85°
69°
3
81°
67°
4
76°
63°
5
75°
61°
6
71°
56°
7
76°
55°
8
76°
58°
9
76°
63°
10
78°
65°
11
73°
54°
12
77°
66°
13
79°
56°
14
66°
55°
15
77°
68°
16
74°
61°
17
71°
56°
18
69°
56°
19
67°
53°
20
65°
52°
21
67°
55°
22
68°
55°
23
70°
57°
24
69°
50°
25
62°
54°
26
69°
56°
27
71°
56°
28
71°
54°
29
67°
54°
30
69°
55°
1
70°
54°
2
64°
54°
3
65°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grimsby
Grimsby's September 2026 forecast shows daily high temperatures ranging from 62° to 79°, with overnight lows between 50° and 68°. The average high for September is 70° with an average low of 56°. 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 Grimsby. See also: October | November | December.
