Only halfway through, hurricane season in 2017 is breaking all kinds of records

Not even halfway into the 2017 hurricane season, and before Irma makes landfall in Florida, tropical mega-storms in the Atlantic basin have already broken several records and challenged others, experts say.

A few that stand out, so far:

So strong for so long

As it swept across the Caribbean, Hurricane Irma generated winds averaging just over 185 mph for more than 33 hours, longer than any super-storm of comparable power ever recorded.

"Such an intensity, for such a long period, has never been observed in the satellite era" that began in the early 1970s, Etienne Kapikian, a forecaster at Meteo France, said.

The runner up is Typhoon Haiyan, which left more than 7,000 people dead or missing in the Philippines and packed winds of the same speed for 24 hours in 2013.

Atlantic surge

Irma was the first hurricane on record to reach Category 5 status — the highest intensity level — while still in the Atlantic Ocean, before entering the balmy waters of the Caribbean Sea, according to the US National Hurricane Center.

Tropical storms draw strength from surface waters warmer than 79 degrees Fahrenheit.

The fact that the swirling mass of clouds and water was able to turbocharge over the Atlantic — whose waters are cooler than the Caribbean but warmer than a few decades ago — is consistent with global warming, scientists say. 

Category 5 tropical storms produce sustained winds of at least 157 mph for at least a minute at a time. Irma has since dropped down to Category 4.

$10 billion cost

Hurricane Irma has so far caused more than $10 billion in economic losses across the Caribbean, making it the costliest storm ever for the region's island nations and territories, according to the Center for Disaster Management and Risk Reduction Technology, based in Karlsruhe, Germany. 

The tally is sure to rise as the storm hits the Bahamas on its way to Florida, but it has already surpassed the damage record set by Hurricanes Ike in 2008, and Hugo in 1989, at $9.4 billion each in today's dollars.

Hardest hit by Irma were Dutch St. Martin ($2.5 billion) and the US Virgin Islands ($2.45 billion), followed by French St. Martin ($1.55 billion) and the British Virgin Islands ($1.4 billion), according to the estimate.

Rain, rain, rain

Tropical Storm Harvey — which made landfall in Texas as a Category 4 hurricane on Aug. 25 — dumped more rain in places than any cyclone ever measured on the continental United States.

In one area southeast of Houston, Harvey unloaded nearly 50 inches of water, breaking the previous record (48 inches) set by Cyclone Amelia.

Second-fastest hurricane

The highest sustained wind speed ever registered for an Atlantic basin storm was 190 mph, for Hurricane Allen, which caused several hundred deaths in Haiti and over a billion dollars in damage.

With consistent winds of 183 mph, Irma shares the title of second-fastest hurricane with Wilma (2005), Gilbert (1988) and the notorious "Labor Day" storm that devastated southern Florida in 1935. 

Three's a crowd

Along with Irma, the Caribbean Sea and Gulf of Mexico is host to two other hurricanes: the Category 4 Jose, projected to leave inhabited islands largely untouched on its northwest trajectory, and Category 2 Katia, due to make landfall in the Mexican state of Veracruz.

Three-at-once is not unprecedented, but it is rare — it last occurred in 2010. Those storms, however, spun harmlessly in the Atlantic, while this time, two of them are hitting land.

The event of four active hurricanes hitting at one time has happened twice — in 1893 and 1998, when Hurricanes Georges, Ivan, Jeanne and Karl all raged simultaneously.

AFP's Marlowe Hood reported from Paris.