There are several ways to measure the strength of a hurricane, from air pressure to sheer size. Although the term "hurricane" is only used in the Atlantic and Eastern Pacific Oceans, the intense circular storms which are also called typhoons or topical cyclones are all the same kind of storm. For this reason, the records shown here are based on worldwide measurements, regardless of whether that particular storm was called a cyclone, typhoon, or hurricane.
However, early historical accounts often lack the measurements available for storms which developed after weather satellites were launched. Estimates of the strength of those storms is based on anecdotal accounts of their damage, which may have have resulted from poor construction, or from an isolated tornado rather than from the main storm system. Thus, where all else is more or less equal, preference is given to storms for which accurate measurements exist.
Most intense hurricane
A hurricane's intensity is measured by the air pressure in its eye. The lowest air pressure ever recorded in the eye of a hurricane was 870 mbars, in the eye of Typhoon Tip. Typhoon Tip formed in the Pacific Ocean in October 1979. Fortunately, it had lost much of its intensity by the time it affected Guam and Japan. Thankfully, fewer than 100 people lost their lives.
Typhoon Tip is also the largest hurricane ever documented. At its greatest diameter, it was 1,380 miles across.
Sustained wind speed is related to air pressure in the eye, although other factors are also involved. At 190 mph, Typhoon Tip shares the record for strongest sustained winds with Typhoon Keith (1997), also in the Pacific Ocean, and Hurricanes Allen (1980) and Camille (1969) in the North Atlantic. Only Hurricane Camille struck land while still at maximum wind speed, killing 259 people.
Deadliest, most damage
These records are usually based on local hurricane preparation and construction methods and costs. They are not an accurate measure of the strength of a hurricane. However, they were still strong enough to cause great harm to those who lived in their path.
Hurricane Katrina is the costliest hurricane to date, with damage estimates of over $100 billion dollars. Most of the damage was caused by the flooding from the broken levies after the hurricane had already passed. This is also how at least 1,836 people lost their lives. Although Hurricane Katrina briefly reached Category 5, it was only Category 3 when it caused the worst damage.
The deadliest hurricane in recorded history was the 1970 cyclone which struck Bhola, Bangladesh. Although it had 115 mph winds, making it the equivalent of a Category 3 hurricane, a storm surge which reached as much as 33 feet struck the unprepared, low-lying, heavily populated islands of the Ganges Delta. The exact death toll will never be known, but at least 300,000 and possibly as many as a million people lost their lives.
Better preparedness, including an improved warning system, made a difference 2 decades later. When a Category 4 hurricane struck the same general area in 1991, the death toll was under 140,000 people. When the Category 5 Cyclone Sidr struck in 2007, the death toll was around 10,000 people. Bangladesh is heading in the right direction, but much more work is needed.