Jefferson County Natural Disasters and Weather Extremes
The chance of earthquake damage in Jefferson County is higher than Montana average and is higher than the national average. The risk of tornado damage in Jefferson County is about the same as Montana average and is much lower than the national average.
Earthquake Index, #6
| Jefferson County | 2.56 |
| Montana | 1.98 |
| U.S. | 1.81 |
The earthquake index value is calculated based on historical earthquake events data using USA.com algorithms. It is an indicator of the earthquake level in a region. A higher earthquake index value means a higher chance of an earthquake.
Volcano Index, #7
| Jefferson County | 0.0000 |
| Montana | 0.0002 |
| U.S. | 0.0023 |
The volcano index value is calculated based on the currently known volcanoes using USA.com algorithms. It is an indicator of the possibility of a region being affected by a possible volcano eruption. A higher volcano index value means a higher chance of being affected.
Tornado Index, #43
| Jefferson County | 2.47 |
| Montana | 7.73 |
| U.S. | 136.45 |
The tornado index value is calculated based on historical tornado events data using USA.com algorithms. It is an indicator of the tornado level in a region. A higher tornado index value means a higher chance of tornado events.
Other Weather Extremes Events
A total of 1,364 other weather extremes events within 50 miles of Jefferson County were recorded from 1950 to 2010. The following is a break down of these events:
| Type | Count | Type | Count | Type | Count | Type | Count | Type | Count |
| Avalanche: | 0 | Blizzard: | 22 | Cold: | 23 | Dense Fog: | 1 | Drought: | 10 |
| Dust Storm: | 0 | Flood: | 46 | Hail: | 440 | Heat: | 2 | Heavy Snow: | 145 |
| High Surf: | 0 | Hurricane: | 0 | Ice Storm: | 4 | Landslide: | 0 | Strong Wind: | 155 |
| Thunderstorm Winds: | 350 | Tropical Storm: | 0 | Wildfire: | 18 | Winter Storm: | 97 | Winter Weather: | 10 |
| Other: | 41 | ||||||||
Volcanos Nearby
No volcano is found in or near Jefferson County.
Historical Earthquake Events
A total of 21 historical earthquake events that had recorded magnitudes of 3.5 or above found in or near Jefferson County.
| Distance (miles) | Date | Magnitude | Depth (km) | Latitude | Longitude |
| 42.0 | 1925-06-28 | 6.8 | N/A | 46 | -111.2 |
| 32.8 | 1935-10-19 | 6.3 | N/A | 46.6 | -112 |
| 34.3 | 1935-10-19 | 6.3 | N/A | 46.62 | -111.97 |
| 34.2 | 1935-10-31 | 6 | N/A | 46.62 | -112 |
| 34.3 | 1935-10-31 | 6 | N/A | 46.62 | -111.97 |
| 38.4 | 1970-06-26 | 4.9 | 26 | 45.6 | -111.8 |
| 27.6 | 1977-03-11 | 4.8 | 5 | 46.13 | -111.48 |
| 29.2 | 1966-03-07 | 4.8 | N/A | 46.3 | -111.5 |
| 26.7 | 1972-11-02 | 4.5 | 5 | 46.1 | -111.5 |
| 38.4 | 1974-07-16 | 4.4 | 10 | 45.84 | -111.37 |
| 27.1 | 1970-10-18 | 4.3 | 15 | 46.2 | -111.5 |
| 26.7 | 1964-08-13 | 4.1 | N/A | 46.5 | -112.2 |
| 29.7 | 1975-05-02 | 4 | N/A | 46.18 | -111.44 |
| 44.0 | 1966-09-19 | 4 | N/A | 45.9 | -111.2 |
| 28.8 | 1984-02-28 | 3.8 | 5 | 46.18 | -111.46 |
| 43.2 | 1976-02-13 | 3.8 | 1 | 46.75 | -112.13 |
| 29.9 | 1983-02-16 | 3.7 | 5 | 45.93 | -111.5 |
| 37.1 | 1965-04-06 | 3.7 | N/A | 45.6 | -111.9 |
| 18.0 | 1976-04-05 | 3.6 | 5 | 46.13 | -111.68 |
| 27.1 | 1972-11-02 | 3.5 | 5 | 46.2 | -111.5 |
| 31.8 | 1972-11-02 | 3.5 | 5 | 46.2 | -111.4 |
Historical Tornado Events
No historical tornado events that had recorded magnitudes of 2 or above found in or near Jefferson County.
No historical earthquake events found in or near Jefferson County.
* The information on this page is based on the global volcano database, the U.S. earthquake database of 1638-1985, and the U.S. Tornado and Weather Extremes database of 1950-2010.