Tornadoes are nature’s most intense atmospheric phenomena, capable of causing widespread destruction. The public often seeks to understand the power of these storms by focusing on the highest recorded intensity ratings. These ratings, represented by the F5 and EF5 categories, mark the pinnacle of tornado ferocity on the established scales. This article focuses on the historical data regarding these extreme events and explains the scientific criteria used for their classification.
The Total Historical Count
The total number of tornadoes rated at the highest intensity level is remarkably low, underscoring their exceptional rarity in the United States. Since the National Weather Service began keeping official, reliable records in 1950, a combined total of only 60 tornadoes have been officially classified as F5 or EF5. This figure represents an average of less than one such event occurring each year across the entire country. The historical record is segmented by the change in classification systems.
Exactly 50 tornadoes were rated F5 during the original Fujita Scale era (1950 through January 31, 2007). Following the scale’s enhancement, 10 tornadoes have been officially rated EF5 since February 1, 2007, to the present. The most recent confirmed EF5 tornado occurred on June 20, 2025, near Enderlin, North Dakota, which ended a historically long drought of these top-tier events. Before that, the last EF5 was recorded on May 20, 2013, in Moore, Oklahoma, creating a twelve-year period without an EF5 rating, the longest such stretch in the modern record.
Defining an F5 and EF5 Tornado
Both the F5 and EF5 ratings represent the maximum level of damage a tornado can inflict, though the wind speed estimates associated with each scale differ. The original Fujita Scale defined an F5 tornado as having estimated three-second wind gusts between 261 and 318 miles per hour. A storm of this magnitude was expected to cause incredible damage, such as lifting well-built frame houses completely off their foundations.
The Enhanced Fujita Scale (EF-Scale) refined this definition, classifying an EF5 tornado as one with estimated three-second wind gusts greater than 200 miles per hour. The key to this top-tier rating is the observation of catastrophic damage to specific structures. This destruction typically involves reinforced concrete structures being severely damaged. Well-constructed homes often have their foundations swept clean of all debris, with the ground sometimes scoured to a depth of half a meter.
The Shift from F-Scale to EF-Scale
The transition from the original Fujita Scale (F-Scale) to the Enhanced Fujita Scale (EF-Scale) was implemented by the National Weather Service on February 1, 2007. The original F-Scale, developed in the 1970s, had limitations because its wind speed estimates were often based on educated guesses and were considered too high by wind engineers. The scale also failed to adequately account for variations in building quality and construction materials.
The EF-Scale addressed these issues by introducing 28 different Damage Indicators (DIs), which include structures like single-family homes, mobile homes, schools, and trees. These indicators, combined with specific Degrees of Damage (DoD), allow surveyors to estimate wind speeds more accurately based on engineering principles. This new methodology provides a more reliable correlation between the observed damage and the wind speed required to cause it. The change means that an F5 tornado rated decades ago, while retaining its F5 historical designation, may have had lower actual wind speeds than the original F-Scale suggested.
Factors Contributing to Extreme Rarity
The extreme rarity of EF5 tornadoes is a direct result of the unique and intense atmospheric conditions required for their formation and sustainment. A storm must first develop into a powerful supercell, which is a thunderstorm characterized by a deep, persistent rotating updraft known as a mesocyclone. This supercell requires an uncommon combination of intense atmospheric instability, high moisture content, and substantial wind shear throughout the lower and mid-levels of the atmosphere.
For a tornado to reach EF5 intensity, the storm must maximize the concentration of rotational energy near the ground, which requires a specific, often short-lived, balance of forces. Furthermore, the EF-Scale is damage-based, meaning a tornado must pass over a well-built structure to demonstrate its full destructive power and earn the highest rating. Many tornadoes may possess EF5-level wind speeds but fail to receive the rating because they only travel over open fields or poorly constructed buildings, which cannot serve as adequate damage indicators. This dependence on both extreme meteorological conditions and the location of impact contributes significantly to the low official count.