Wyoming, often associated with high mountains and the Rocky Mountains, might seem an unlikely location for tornado activity. The state’s eastern half, however, lies directly on the High Plains, where conditions necessary for severe storm development frequently converge. Tornadoes do occur in Wyoming, bringing a unique set of hazards that differ significantly from those in the traditional “Tornado Alley.” This activity is heavily concentrated in specific regions and during certain times of the year.
Tornado Frequency and General Statistics
Wyoming’s tornado frequency is relatively low compared to states in the core of the central Plains, but it still experiences consistent activity. Historical data indicates the state averages between six and twelve tornadoes each year, with an average of 9.1 per year reported over the last decade. This number places Wyoming far behind neighboring Colorado, which recorded nearly three times as many events during a comparable period. The state’s location west of the main “Tornado Alley” results in diminished frequency and intensity, as the Rocky Mountains disrupt air flows from the Gulf of Mexico.
The tornadoes that form in Wyoming are typically much shorter and narrower than their counterparts further east. The average path length is about three miles, and the average width is about 79 yards. This short-track nature means most tornadoes affect sparsely populated areas, contributing to the state having some of the lowest weather-related fatality rates in the nation. The annual occurrence of these events confirms that the risk is a persistent part of Wyoming’s severe weather climatology.
Geographic Hotspots in Wyoming
The distribution of tornado activity is heavily skewed toward the eastern side of the state, where the terrain is predominantly open high prairie. This region, especially the southeastern corner, is the most susceptible because it is closest to the air mass collision zone that fuels severe weather across the central United States. The flow of warm, moist air from the Gulf of Mexico pushes northward onto the High Plains, providing the necessary low-level moisture and instability.
Laramie County, which includes Cheyenne, has historically recorded the highest number of tornadoes in the state. This county, along with Campbell and Goshen counties, accounts for over 40% of all confirmed tornado events. The relative safety of the western half of the state is due to the significant elevation gain provided by the mountainous landscape. The high-altitude terrain limits the development of strong, rotating thunderstorms, known as supercells, by disrupting the low-level wind shear and moisture supply. Teton County, located deep in the mountains, has recorded only a negligible number of tornadoes in comparison to the eastern plains.
Peak Season and Typical Intensity
The tornado season in Wyoming is concentrated over a short period, peaking in the early summer months. June is statistically the most active month, though the season typically runs from late May through early July. The highest probability for a touchdown occurs in the late afternoon and early evening, between 3:00 PM and 7:00 PM, when daytime heating and atmospheric instability are greatest.
The majority of tornadoes recorded in Wyoming are weak, falling into the EF0 or EF1 categories on the Enhanced Fujita Scale. The weakest intensity, EF0, occurs more than half the time, meaning most events cause minimal damage, often affecting only open rangeland. While less common, stronger tornadoes are possible, with significant events rated EF2 or higher occurring in about four out of every 100 tornadoes. The strongest tornado on record was an F4 that occurred in 1987 in Teton County, striking at an extremely high elevation of between 8,500 and 10,000 feet.