Most Flood-Prone Counties in Pennsylvania

Based on NOAA Storm Events Database records from 1996 to 2025, these are the Pennsylvania counties with the most recorded flood events. Allegheny County tops the list with 621 events. The data includes river floods, flash floods, coastal flooding, and hurricane-related flooding.

Rank	County	Total Events	River Floods	Flash Floods
1	Allegheny County	621	125	496
2	Westmoreland County	322	84	238
3	Philadelphia County	301	97	143
4	Chester County	295	70	223
5	Delaware County	273	71	144
6	Montgomery County	265	71	192
7	Berks County	240	61	177
8	Washington County	215	72	143
9	Bradford County	199	40	159
10	Bucks County	195	53	122
11	Lancaster County	167	60	106
12	Beaver County	158	63	95
13	Fayette County	157	38	119
14	Luzerne County	140	29	111
15	York County	140	43	96
16	Northampton County	139	38	99
17	Lawrence County	128	34	94
18	Lehigh County	128	31	95
19	Butler County	115	40	75
20	Jefferson County	109	55	54
21	Susquehanna County	106	9	97
22	Mercer County	105	23	82
23	Venango County	100	29	71
24	Lackawanna County	98	14	84
25	Greene County	93	38	55
26	Somerset County	86	24	61
27	Monroe County	85	21	63
28	Cumberland County	83	44	38
29	Lycoming County	83	44	38
30	Erie County	82	16	60
31	Armstrong County	82	31	51
32	Indiana County	80	24	56
33	Dauphin County	79	36	42
34	Crawford County	78	15	63
35	Lebanon County	78	34	43
36	Clarion County	70	21	49
37	Wayne County	67	10	57
38	Wyoming County	67	25	42
39	Huntingdon County	66	35	30
40	Carbon County	61	19	41
41	Franklin County	61	16	44
42	Bedford County	59	19	39
43	Schuylkill County	59	21	37
44	Blair County	58	20	37
45	Adams County	53	22	30
46	Clearfield County	50	13	37
47	Tioga County	50	22	27
48	Cambria County	49	13	35
49	Northumberland County	48	20	27
50	Columbia County	47	16	30
51	Union County	45	24	20
52	Perry County	42	23	18
53	Clinton County	41	29	11
54	Centre County	38	15	22
55	Sullivan County	38	14	23
56	McKean County	36	9	26
57	Snyder County	36	18	17
58	Warren County	35	8	27
59	Fulton County	29	13	15
60	Potter County	29	10	18
61	Pike County	27	10	17
62	Montour County	25	12	12
63	Juniata County	23	7	15
64	Forest County	17	5	12
65	Mifflin County	16	7	8
66	Elk County	14	7	7
67	Cameron County	12	7	5

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

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Most Flood-Prone Counties in Pennsylvania

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