Wyoming volcanic activity risk
Teton County has the highest volcanic activity risk in Wyoming, scoring 65.1 out of 100 — rated "Very Low" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
|---|---|---|---|
| 1 | Teton County | 65.1 | Very Low |
| 2 | Park County | 44 | Very Low |
| 3 | Lincoln County | 41.7 | Very Low |
| 4 | Big Horn County | 33.2 | Very Low |
| 5 | Washakie County | 30.9 | Very Low |
| 6 | Fremont County | 22.5 | Very Low |
| 7 | Sublette County | 19.5 | Very Low |
| 8 | Hot Springs County | 13.4 | Very Low |
| 9 | Sheridan County | 11.1 | Very Low |
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.
Volcanic Activity risk nationally:
Other hazard risks in Wyoming:
Frequently asked questions
What is the highest volcanic activity risk county in Wyoming?
Teton County, WY has the highest volcanic activity risk in Wyoming, with a FEMA National Risk Index score of 65.1 out of 100 (rated "Very Low").
What causes volcanic activity risk in Wyoming?
Volcanic activity risk reflects expected losses from lava flows, tephra fall, lahars (volcanic mudflows), and volcanic gases. The highest-risk counties are in Washington (Mt. Rainier), Oregon (Mt. Hood), and Hawaii (Kilauea, Mauna Loa). Alaska's Aleutian chain contains many active volcanoes affecting nearby communities and trans-Pacific air traffic. Volcanic ashfall events are reported at forecast-zone level in NOAA Storm Events and are not included in county-level counts.