Isabel. Ivan. Ike. Irene. And now Irma. These terrible hurricanes, all of which have occurred since 2003, begin with a common vowel. They haven’t all started with the same letter by chance — there is some science behind the abundance of notorious storms starting with the letter “I.”

Since 1953, storms have been given human names to make identifying them more convenient. For 26 years they were given only female names, but in 1979 the male-female alternating alphabetical lists that we use today were introduced.

Names associated with storms that cause severe loss of life or property damage are retired by the World Meteorological Organization. The idea of permanently retiring a storm names began after the 1954 hurricane season when Carol, Edna and Hazel ravaged the East Coast.

Since that fateful year, a total of 84 storm names have been retired, and those beginning with “I” make up the majority of them.

This is not entirely surprising: “I”-name storms tend to coincide near the average peak of the hurricane season. With ocean temperatures warm and hostile winds shear, conditions are prime for hurricane development

Over the past 50 years, the average “I” or ninth named storm forms on Sept. 30. But during active seasons, which produce some of the most extreme hurricanes, the average date creeps up by about two weeks, coinciding with the heart of the season, which spans June 1 to Nov. 30.

While we remember with horror storms like Isabel and Ivan, terrible “I” storms haven’t just afflicted the United States. Putting the 10 retired “I” storms on a map reveals that they had an effect on many countries.

Irma has already caused tremendous harm in the Caribbean, and a hurricane disaster in Florida seems unavoidable. It seems destined to become the next “I” storm whose name will never describe another hurricane.

Jason Samenow contributed to this report.