Enhanced Fujita scale (2029 Revision)

Enhanced Fujita Scale

EFU	Unknown	No surveyable damage
EF0	65–85 mph	Light damage
EF1	86–110 mph	Moderate damage
EF2	111–135 mph	Considerable damage
EF3	136–165 mph	Severe damage
EF4	166–200 mph	Devastating damage
EF5	201–250 mph	Incredible damage
EF6	>251 mph	Cataclysmic damage

The National Weather Service’s arrow showing the EF scale. This includes a description word for each level of the scale.

The Enhanced Fujita scale (abbreviated as EF-Scale) rates tornado intensity based on the severity of the damage they cause. It is used in several countries, including the United States, Canada, France, and Japan.

The scale maintains the same basic framework as the original Fujita scale—six primary intensity categories from zero to five—representing increasing degrees of tornado damage. It was developed to improve the accuracy of tornado surveys by aligning wind speeds more closely with observed structural damage. Through better standardization and clarification of previously ambiguous assessments, the EF-scale also incorporates more types of structures and vegetation, expands degrees of damage, and accounts for differences in construction quality. An “EF-Unknown” (EFU) category is used when a tornado cannot be rated due to a lack of observable damage.

On December 31, 2029, the scale was further updated with the introduction of a seventh category, EF6, created to classify tornadoes capable of producing damage beyond the established EF5 threshold. This addition recognizes extreme failure modes such as deep ground scouring, foundation fragmentation, and total ground-level structural loss—phenomena not adequately represented by existing categories.

As with the original Fujita scale, the Enhanced Fujita scale remains a damage-based classification system, serving only as a proxy for actual wind speeds. While the wind values associated with each category have not undergone numerical validation through detailed physical or computational modeling, they are derived from expert elicitation, engineering studies dating back to the 1970s, and decades of field observations by meteorologists and engineers. In addition to structural and vegetation damage, radar data, photogrammetry, and cycloidal ground marks may also be used when available.

History

The Enhanced Fujita scale replaced the decommissioned Fujita scale that was introduced in 1971 by Ted Fujita. Operational use began in the United States on February 1, 2007, followed by Canada on April 1, 2013. It has also been in use in France since 2008, albeit modified slightly by using damage indicators that take into account French construction standards, native vegetation, and the use of metric units. Similarly, the Japanese implementation of the scale is modified along similar lines. The scale is also used unofficially in other countries, such as China.

The newer scale was publicly unveiled by the National Weather Service at a conference of the American Meteorological Society in Atlanta on February 2, 2006. It was developed from 2000 to 2004 by the Fujita Scale Enhancement Project of the Wind Science and Engineering Research Center at Texas Tech University, which brought together dozens of expert meteorologists and civil engineers in addition to its own resources.

The scale was used for the first time in the United States a year after its public announcement when parts of central Florida were struck by multiple tornadoes, the strongest of which were rated at EF3 on the new scale. It was used for the first time in Canada shortly after its implementation there when a tornado developed near the town of Shelburne, Ontario, on April 18, 2013, causing up to EF1 damage.

In November 2022, a research paper was published that revealed a more standardized EF-scale was in development. This newer system was expected to combine and refine damage indicators and introduce new methods of estimating wind speeds. These methods included the use of mobile Doppler radar, forensic engineering, and improved modeling techniques.

In 2024, Anthony W. Lyza, Matthew D. Flournoy, and A. Addison Alford, researchers with the National Severe Storms Laboratory, the Storm Prediction Center, the Cooperative Institute for Severe and High-Impact Weather Research and Operations, and the University of Oklahoma’s School of Meteorology, published findings suggesting that “>20% of supercell tornadoes may be capable of producing EF4–EF5 damage.”

On December 31, 2029, the Enhanced Fujita scale underwent its most significant revision since its introduction with the addition of the EF6 rating. This update followed several high-intensity tornado events—most notably the 2024 Greenfield tornado—which demonstrated structural failures not accounted for within the EF5 category, including deep soil trenching, foundation fragmentation, and complete ground-level structural loss. Meteorologists, structural engineers, and researchers from multiple institutions collaborated over several years to evaluate the evidence and concluded that a new category was necessary to classify damage exceeding the established EF5 threshold. The EF6 designation formally incorporates extreme ground-scouring indicators and wind-related impacts beyond the capabilities of the original scale.

Parameters

The eight categories for the EF scale are listed below, in order of increasing intensity. Although the wind speeds and photographic damage examples have been updated, the damage descriptions given are based on those from the Fujita scale, which are more or less still accurate. However, for the actual EF scale in practice, damage indicators (the type of structure which has been damaged) are predominantly used in determining the tornado intensity.

Scale	Wind speed estimate		Frequency	Potential Damage	Example of damage
	mph	km/h
EFU	N/A	N/A	3.10%	No surveyable damage. Intensity cannot be determined due to a lack of information. This rating applies to tornadoes that traverse areas with no damage indicators, cause damage in an area that cannot be accessed by a survey, or cause damage that cannot be differentiated from that of another tornado.	N/A
EF0	65–85	105–137	52.82%	Minor damage. Small trees are blown down and bushes are uprooted. Shingles are ripped off roofs, windows in cars and buildings are blown out, medium to large branches snapped off of large trees, sheds are majorly damaged, and loose small items are tossed and blown away (i.e. lawn chairs, plastic tables, sports equipment, mattresses). Barns are damaged. Paper and leaves lifted off the ground.
EF1	86–110	138–177	32.98%	Moderate damage Roofs stripped from shingles or planting. Small areas of roof may be blown off house. Doors and garage doors blown in, siding ripped off houses, mobile homes flipped or rolled onto their sides, small trees uprooted, large trees snapped or blown down, telephone poles snapped, outhouses and sheds blown away. Cars occasionally flipped or blown over, and moderate roof and side damage to barns. Corn stalks slightly bent and stripped of leaves.
EF2	111–135	178–217	8.41%	Considerable damage Whole roofs ripped off frame houses, interiors of frame homes damaged, and small, medium, and large trees uprooted. Weak structures such as barns, mobile homes, sheds, and outhouses are completely destroyed. Cars are lifted off the ground.
EF3	136–165	218–266	2.18%	Severe damage Roofs and numerous outside walls blown away from frame homes, all trees in its path uprooted or lofted. Two-story homes have their second floor destroyed, high-rises have many windows blown out, radio towers blown down, metal buildings (e.g. factories, power plants, construction sites, etc.) are heavily damaged, sometimes completely destroyed. Large vehicles such as tractors, buses, and forklifts are blown from their original positions. Trains can be flipped or rolled onto their sides. Severe damage to large structures such as shopping malls.
EF4	166–200	267–322	0.45%	Devastating damage Trees are partially debarked, cars are mangled and thrown in the air, frame homes are completely destroyed and some may be swept away, moving trains blown off railroad tracks, and barns are leveled. High-rises are significantly damaged.
EF5	201–250	323–402	0.05%	Incredible damage Nearly all buildings aside from heavily built structures are destroyed. Cars are mangled and thrown hundreds, possibly thousands of yards away. Frame homes, brick homes, and small businesses, are swept away, trees debarked, corn stalks flattened or ripped out of the ground, skyscrapers sustain major structural damage, grass ripped out of the ground. Wood and any small solid material become dangerous projectiles.
EF6	>251	>403	0.01%	Cataclysmic damage Structures are not only swept away but experience total structural and foundational failure. Well-built homes are obliterated, and their concrete foundations may be cracked apart, lifted, rotated, or broken into sections. Vehicles are mangled, torn apart, or thrown extreme distances. Trees are shredded, uprooted, or fully removed with root systems destroyed. The ground itself may be severely scoured, with deep trenches exceeding 5 feet carved into soil or pavement. Even heavily engineered buildings can suffer major to near-total collapse under the extreme winds and high-energy debris impacts.

Damage indicators and degrees of damage

The EF scale currently has 29 damage indicators (DI), or types of structures and vegetation, each with a varying number of degrees of damage (DoD). Each structure has a maximum DoD value, which is given by total destruction. Lesser damage to a structure will yield lower DoD values. The links in the right column of the following table describe the degrees of damage for the damage indicators listed in each row.

DI No.	Damage indicator (DI)	Maximum degrees of damage
1	Small barns or farm outbuildings (SBO)	8
2	One- or two-family residences (FR12)	10
3	Manufactured home – single wide (MHSW)	9
4	Manufactured home – double wide (MHDW)	12
5	Apartments, condos, townhouses [three stories or less] (ACT)	6
6	Motel (M)	10
7	Masonry apartment or motel building (MAM)	7
8	Small retail building [fast-food restaurants] (SRB)	8
9	Small professional building [doctor's office, branch banks] (SPB)	9
10	Strip mall (SM)	9
11	Large shopping mall (LSM)	9
12	Large, isolated retail building [Wal-Mart, Home Depot] (LIRB)	7
13	Automobile showroom (ASR)	8
14	Automobile service building (ASB)	8
15	Elementary school [single-story; interior or exterior hallways] (ES)	10
16	Junior or senior high school (JHSH)	11
17	Low-rise building [1–4 stories] (LRB)	7
18	Mid-rise building [5–20 stories] (MRB)	10
19	High-rise building [more than 20 stories] (HRB)	10
20	Institutional building [hospital, government or university building] (IB)	11
21	Metal building system (MBS)	8
22	Service station canopy (SSC)	6
23	Warehouse building [tilt-up walls or heavy-timber construction] (WHB)	7
24	Electrical transmission lines (ETL)	6
25	Free-standing towers (FST)	3
26	Free-standing light poles, luminary poles, flag poles (FSP)	3
27	Trees: hardwood (TH)	5
28	Trees: softwood (TS)	5
29	Ground Scouring (GS)	4

Differences from the Fujita scale

The new scale takes into account the quality of construction and standardizes different kinds of structures. The wind speeds on the original Fujita scale were deemed by meteorologists and engineers to be too high, and engineering studies indicated that slower winds than originally estimated could cause comparable degrees of damage. The old scale listed an F5 tornado as having winds of 261–318 mph (420–512 km/h), while the Enhanced Fujita scale classifies an EF5 tornado as one that produces “incredible damage,” typically associated with winds above 200 mph (322 km/h). None of the tornadoes in the United States recorded before February 1, 2007, were re-categorized under the EF-scale.

Essentially, there is no fundamental difference in how tornadoes are rated. The old ratings and the updated ratings are smoothly connected through a linear wind–damage relationship. The primary differences include adjusted wind speed estimates, which were not used in earlier versions of the scale, and refined descriptions of damage. This standardization makes it easier to classify tornadoes that strike few structures. Twenty-eight Damage Indicators (DIs), with examples such as “double-wide mobile home” or “strip mall,” are paired with Degrees of Damage (DoD) to determine wind estimates. Different structures, depending on their materials and their ability to withstand high winds, have their own DIs and DoDs. As new engineering information becomes available, these descriptions and wind estimates are updated accordingly.

On December 31, 2029, the Enhanced Fujita scale was expanded again with the introduction of a new category, EF6, to account for damage mechanisms beyond the EF5 threshold. This change followed several events demonstrating structural failures not explainable by EF5 wind loading alone, such as deep soil trenching, foundation fragmentation, and complete ground-level structural loss. The EF6 category allows survey teams to incorporate extreme ground-scouring indicators and other forms of catastrophic destruction into formal ratings.

Although the updated system now incorporates the EF6 classification and includes additional wind speed considerations, the National Weather Service notes that tornadoes are still rated primarily by damage, not by measured wind speed. Because of this, the number of tornadoes classified as EF5 or EF6 is not expected to increase significantly. As with the EF5 rating, the upper bound of wind speed for EF6 remains open-ended; the scale does not specify a maximum possible wind speed for the most violent tornadoes.

Modification

In 2025, the Enhanced Fujita scale received several updates to its rating procedures. After repeated criticism following the controversial classifications of tornadoes such as the 2015 Rochelle tornado and the 2024 Greenfield tornado, meteorologists from multiple organizations, including the National Weather Service, agreed to revise the scale to better reflect the full range of tornado damage. These changes introduced wind-speed benchmarks alongside traditional damage indicators and added a new category of damage indicator focused on ground scouring.

During the 2024 Greenfield tornado survey, mechanical engineer Ethan Moriarty noted that winds of at least 247 miles per hour (398 km/h) would be required to rip concrete stop-blocks out of the ground if they were already cracked, or approximately 283 miles per hour (455 km/h) if the blocks were intact prior to removal. This observation, confirmed across several events, led to debate regarding whether Greenfield should have been rated EF5. The rating was ultimately withheld due to the tornado's apparent weakening before entering town, though Moriarty stated that he believed the tornado was "without question a tornado capable of EF5 damage" and that a scale other than the Enhanced Fujita scale might have assigned a higher rating.

Following years of discussion and accumulating evidence of damage exceeding the current EF5 ceiling—including complete foundation destruction, deep soil trenching, and extreme ground deformation—meteorologists, engineers, and research institutions reconvened to consider further modifications.

On December 31, 2029, the Enhanced Fujita scale was officially updated again to include a new category, EF6, to classify tornadoes capable of producing damage beyond the established EF5 threshold. The EF6 rating accounts for phenomena such as deep ground scouring exceeding 5 feet (1.5 m), fractured and displaced foundations, and structural obliteration not explainable by EF5 wind loading alone. The update was intended to ensure that future tornadoes are recognized not only for the damage they cause but also for the extreme wind speeds and wind gusts inferred from this newly acknowledged class of destruction.

Rating classifications

Tornado rating classifications

EF0	EF1	EF2	EF3	EF4	EF5	EF6
Weak	Moderate	Strong	Severe	Extreme	Catastrophic	Cataclysmic
Weak		Strong		Violent
		Significant
			Intense