California inland flooding risk

58 counties scored 9 rated Very High

Los Angeles County has the highest inland flooding risk in California, scoring 100 out of 100 — rated "Very High" by FEMA's National Risk Index. Recorded inland flooding events across California have increased 53% over the past five years compared to the prior five-year period.

#	County	NRI score	Rating	NOAA events 2016–2026
1	Los Angeles County	100	Very High	107
2	Riverside County	99.9	Very High	210
3	Orange County	99.8	Very High	75
4	San Bernardino County	99.8	Very High	448
5	Santa Clara County	99.8	Very High	117
6	Alameda County	99.7	Very High	144
7	San Diego County	99.7	Very High	250
8	Contra Costa County	99.5	Very High	49
9	Ventura County	99.3	Very High	46
10	Sonoma County	99.2	Relatively High	238
11	Sacramento County	99	Relatively High	148
12	Fresno County	98.7	Relatively High	271
13	San Francisco County	98.6	Relatively High	78
14	Santa Barbara County	98.6	Relatively High	47
15	Kern County	98.5	Relatively High	319
16	San Mateo County	98.4	Relatively High	55
17	Tulare County	98.1	Relatively High	189
18	San Joaquin County	97.7	Relatively High	47
19	Solano County	97.4	Relatively High	19
20	Monterey County	97.3	Relatively High	117
21	San Luis Obispo County	96.7	Relatively High	26
22	Marin County	96.5	Relatively High	76
23	Santa Cruz County	96.2	Relatively High	57
24	Stanislaus County	96	Relatively High	14
25	Napa County	95.8	Relatively High	29
26	Placer County	95.8	Relatively High	46
27	Mendocino County	95.1	Relatively High	64
28	Shasta County	94.8	Relatively High	64
29	Merced County	94.7	Relatively High	109
30	Humboldt County	94.2	Relatively High	89
31	Imperial County	94.1	Relatively High	98
32	Lake County	94.1	Relatively High	24
33	Madera County	94	Relatively High	54
34	Butte County	93.2	Relatively Moderate	89
35	El Dorado County	91.7	Relatively Moderate	45
36	Siskiyou County	90.9	Relatively Moderate	7
37	Tehama County	90	Relatively Moderate	49
38	Nevada County	89.9	Relatively Moderate	25
39	Yolo County	89.6	Relatively Moderate	46
40	Plumas County	87.9	Relatively Moderate	12
41	Kings County	87.7	Relatively Moderate	23
42	Yuba County	83.8	Relatively Moderate	10
43	Tuolumne County	81	Relatively Moderate	18
44	Trinity County	79	Relatively Moderate	3
45	Del Norte County	77.8	Relatively Moderate	7
46	Calaveras County	77.6	Relatively Moderate	23
47	Lassen County	74.4	Relatively Moderate	8
48	Sutter County	71.4	Relatively Low	13
49	Mariposa County	70.8	Relatively Low	80
50	Amador County	70	Relatively Low	11
51	San Benito County	69.4	Relatively Low	22
52	Inyo County	61.6	Relatively Low	136
53	Mono County	46.9	Relatively Low	8
54	Modoc County	44.8	Relatively Low	7
55	Glenn County	42.3	Relatively Low	19
56	Colusa County	37.9	Relatively Low	17
57	Sierra County	37.7	Relatively Low	2
58	Alpine County	11.2	Very Low	1

Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.

Inland Flooding risk nationally:

Top 50 US counties

Other hazard risks in California:

Wildfire Coastal Flooding Earthquake Heat Wave Tornado Hurricane Hail Strong Wind Winter Weather Ice Storm Cold Wave Lightning Drought Landslide Avalanche Tsunami Volcanic Activity

Frequently asked questions

What is the highest inland flooding risk county in California?

Los Angeles County, CA has the highest inland flooding risk in California, with a FEMA National Risk Index score of 100 out of 100 (rated "Very High").

How many counties in California are rated Very High for inland flooding risk?

9 of 58 scored California counties are rated "Very High" for inland flooding risk by FEMA's National Risk Index.

What causes inland flooding risk in California?

Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.