Throughout the world, agricultural areas (e.g., the midwestern United States and farming regions within other countries like Brazil and Argentina) tend to be at higher risk for the development of tornadoes because certain weather patterns that promote good crop yields may also contribute to the development of tornadoes (10). In addition to geographic factors, the time of day and the time of year also affect a population's risk from tornadoes. For example, late afternoon is the time of day when tornadoes are most likely to occur. Seasonal variation associated with the development of tornadoes means that the risk from tornadoes to the population at any given location is not constant throughout the year. In the United States, January is the month when the fewest tornadoes occur, and May is the month when the most tornadoes occur (10). Other natural factors that promote the development of tornadoes include weather phenomena such as hurricanes. Hurricane Beulah, for example, which struck in 1967, is credited with spawning 115 tornadoes in the coastal region of Texas (2).