Most Flood-Prone Counties in Montana

Based on NOAA Storm Events Database records from 1996 to 2025, these are the Montana counties with the most recorded flood events. Valley County tops the list with 116 events. The data includes river floods, flash floods, coastal flooding, and hurricane-related flooding.

Rank	County	Total Events	River Floods	Flash Floods
1	Valley County	116	78	38
2	Phillips County	51	38	13
3	Roosevelt County	47	22	25
4	Lewis and Clark County	39	18	21
5	Yellowstone County	37	13	24
6	Garfield County	36	16	20
7	Musselshell County	35	9	26
8	Richland County	33	17	16
9	Powder River County	31	8	23
10	Cascade County	30	15	15
11	Custer County	30	10	20
12	Rosebud County	28	12	16
13	Dawson County	27	17	10
14	Big Horn County	24	11	13
15	McCone County	24	8	16
16	Petroleum County	24	17	7
17	Missoula County	24	21	3
18	Blaine County	22	17	5
19	Ravalli County	22	13	9
20	Prairie County	21	8	13
21	Carbon County	20	8	12
22	Daniels County	17	9	8
23	Stillwater County	17	5	12
24	Wibaux County	17	9	8
25	Fergus County	16	11	5
26	Flathead County	16	11	5
27	Fallon County	15	1	14
28	Golden Valley County	14	6	8
29	Sheridan County	13	9	4
30	Gallatin County	12	10	2
31	Treasure County	11	8	3
32	Carter County	10	4	6
33	Sweet Grass County	10	5	5
34	Chouteau County	9	7	2
35	Teton County	9	6	3
36	Wheatland County	9	5	4
37	Madison County	9	9	0
38	Hill County	8	6	2
39	Lincoln County	8	8	0
40	Sanders County	8	7	1
41	Beaverhead County	8	4	4
42	Glacier County	8	6	2
43	Pondera County	8	6	2
44	Jefferson County	7	4	3
45	Silver Bow County	7	1	6
46	Toole County	7	2	5
47	Park County	7	6	1
48	Meagher County	6	4	2
49	Granite County	6	3	3
50	Judith Basin County	6	5	1
51	Powell County	5	3	2
52	Broadwater County	5	3	2
53	Deer Lodge County	5	3	2
54	Mineral County	4	3	1
55	Lake County	3	2	0
56	Liberty County	2	2	0

Source: NOAA Storm Events Database (1996–2025).

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