Hurricane Isaias Is the Latest First Hurricane Since 1914

Hurricane Isaias just did something the Atlantic hasn't seen in more than a century: it became the latest-in-the-season first hurricane of the year since 1914. The storm is spinning in the Gulf of Mexico and heading for the US coast, and it's a messy tug-of-war between a monster El Niño and an overheated ocean.

From 40 mph to 80 mph in a day

According to the Associated Press, via ABC News, the storm rapidly intensified from 40 mph to 80 mph (64 to 129 kph) in a single day. By late Wednesday it officially became a hurricane, and Colorado State University researcher Phil Klotzbach says that makes it the latest first Atlantic hurricane to form in a season since 1914.

That's wild for a season that barely got going. El Niño, the natural warming of parts of the Pacific that warps weather worldwide, spent months smothering almost every wisp of a storm in the Atlantic. Its high-altitude winds, called wind shear, push the tops of storms sideways and keep them from forming the tight circular eyewall they need to power up.

Why the Gulf let this one slip through

The Gulf of Mexico is less affected by El Niño than the main Atlantic, and October is prime time for storms to pop up there. A window of moderate shear opened for a couple of days, and that was enough. As Klotzbach put it, the warm waters and high moisture won.

Those waters are no joke. The Gulf is about 2.7 degrees Fahrenheit (1.5 C) warmer than normal, with temperatures around 86 F (30 C). Climate Central's Kristina Dahl says that kind of heat is 100 to 500 times more likely because of climate change from burning coal, oil and gas.

What to expect at landfall

Forecasters expect the storm to flirt with 111 mph winds on Friday, which could briefly touch major hurricane status. But the shear is forecast to ramp up from around 20 mph to 52 mph before it arrives, so Klotzbach expects it to come ashore as a strong Category 1 or weak Category 2.

Landfall is forecast somewhere between the Mississippi and Alabama coast and the Florida Panhandle late Friday night or early Saturday. Less than a major storm doesn't mean harmless. The National Hurricane Center is calling the storm surge life-threatening and warning about urban, river and flash flooding across the Southeast this weekend.

Climate change is the long game

Here's the part that matters beyond one storm. According to NPR, even as El Niño limited this year's Atlantic activity, climate change is making hurricanes more intense. Dahl says the surge will be deeper and reach farther because of sea level rise, with about six and a half inches of rise in this region over the past 100 years attributed directly to climate change.

A warmer atmosphere also holds more moisture and then dumps it, which means heavier rain and worse flooding. Dahl described climate change as the long-term big kahuna warming everywhere, with El Niño as just icing on the cake.

That El Niño is far from done. The World Meteorological Organization said this week it expects the event to intensify and last through February 2027, which we broke down in our climate coverage. For you, the practical takeaway is simple: a quiet season on paper can still deliver one dangerous storm.

What to do if you're on the Gulf Coast

Hurricane Isaias is also a reminder that forecasts can change fast. Storms that look weak on Monday can become Category 2 hurricanes by Thursday, which is exactly what happened here. Rapid intensification is one of the trickiest things for forecasters, and warmer oceans are making it more common. If your area is under a watch or warning, treat it seriously, and make sure friends, family and neighbours who might not be online know what's coming.

If you live anywhere from Mississippi to the Florida Panhandle, check evacuation zones now, charge your phone, and follow local officials and the National Hurricane Center for updates. Surge and flooding, not wind, are usually what hurt people most, so don't wait for the storm to look scary on your street.

We'll keep tracking Hurricane Isaias as it nears the coast. For more on how a warming planet is rewriting the weather, keep an eye on our world desk.

Sources: reporting from the Associated Press via ABC News and NPR.