Resolution criteria:

This market will resolve to "Yes" if 50 or more tornadoes rated EF2 or higher occur in the continental United States during May 2025. The Enhanced Fujita (EF) scale classifies tornadoes based on estimated wind speeds and resulting damage, with EF2 tornadoes having wind speeds between 111 and 135 mph. Official confirmation from the National Weather Service (NWS) or the Storm Prediction Center (SPC) will be used to determine the count. If fewer than 50 such tornadoes are confirmed, the market will resolve to "No."

Background:

May is historically the peak month for tornado activity in the United States. Between 1991 and 2020, an average of 294 tornadoes occurred each May, with approximately 20% classified as significant (EF2 or higher), equating to about 59 significant tornadoes on average. (foxweather.com, ustornadoes.com)

In May 2024, the U.S. experienced 570 tornadoes, significantly above the 1991-2020 average. This included multiple EF2+ tornadoes, contributing to May 2024 being the second most active May on record. (disasterphilanthropy.org)

The number of EF2+ tornadoes in May can vary significantly from year to year, influenced by atmospheric conditions, climate patterns, and other factors. For instance, in May 2021, there were 288 preliminary tornado reports, with no EF3+ tornadoes reported, marking the first time since records began in 1950 that no EF3+ tornadoes occurred during May. (ncei.noaa.gov)

Given this variability, predicting whether May 2025 will see 50 or more EF2+ tornadoes involves considering both historical averages and current meteorological forecasts.