S
M
T
W
T
F
S
26
50°
27°
27
53°
26°
28
56°
36°
29
62°
36°
30
65°
31°
1
75°
42°
2
73°
46°
3
75°
44°
4
69°
40°
5
64°
44°
6
76°
45°
7
78°
47°
8
76°
45°
9
73°
44°
10
71°
41°
11
70°
41°
12
74°
45°
13
73°
44°
14
68°
40°
15
62°
35°
16
62°
36°
17
63°
36°
18
64°
41°
19
63°
44°
20
61°
40°
21
63°
40°
22
63°
38°
23
61°
37°
24
63°
38°
25
64°
38°
26
70°
41°
27
72°
46°
28
73°
43°
29
71°
46°
30
66°
45°
31
69°
47°
1
68°
44°
2
66°
41°
3
72°
48°
4
66°
45°
5
68°
47°
6
69°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Flathead Reservation
Flathead Reservation's May 2026 forecast shows daily high temperatures ranging from 61° to 78°, with overnight lows between 35° and 50°. The average high for May is 68° with an average low of 43°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Flathead Reservation. See also: June | July | August.