Hurricane season 2023 has begun in the Atlantic. Here's what to expect and when it ends.
It's here: The 2023 Atlantic hurricane season has begun.
Though tropical storms and hurricanes can form year-round, most brew during the six-month Atlantic hurricane season, which officially runs from June 1 to Nov. 30 each year. In fact, 97% of all tropical cyclones in the Atlantic form during the season.
"Tropical cyclone" is an umbrella term that includes tropical storms and hurricanes. A tropical storm gets a name when its sustained winds reach 39 mph; a tropical storm becomes a hurricane when its sustained winds reach 74 mph.
The Atlantic hurricane basin includes storms that form in the Atlantic Ocean, Caribbean Sea and Gulf of Mexico.
Based on the 30-year climate period from 1991 to 2020, an average Atlantic hurricane season has 14 named storms, of which seven become hurricanes. Of those seven hurricanes, three are classified as "major" hurricanes − Category 3, 4 or 5 on the Saffir-Simpson hurricane wind scale.
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When do Atlantic hurricanes typically form? What are hurricane season months?
Although the official season lasts from June to November, the primary time of year for hurricanes to form is midsummer to midautumn, specifically July to October.
That's because the meteorological ingredients necessary for hurricane formation are all available at that time of year. Ingredients include ocean water of at least 80 degrees, a tropical atmosphere that produces plenty of thunderstorms, a lack of wind shear, and a substantial amount of large-scale spin.
The first named storm typically forms in mid- to late June, the first hurricane tends to form in early to mid-August, and the first major hurricane forms in late August or early September.
The statistical peak of the Atlantic hurricane season is Sept. 10.
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What about eastern Pacific hurricanes? When is the eastern Pacific hurricane season?
The eastern Pacific hurricane season runs from May 15 to Nov. 30. The eastern Pacific basin extends from Mexico and Central America westward to 140° west longitude in the Pacific Ocean.
In the eastern Pacific, the peak in activity is late August, but this peak is less pronounced than the peak in the Atlantic. Relatively high levels of activity in the eastern Pacific tend to be spread out over a longer portion of the season than in the Atlantic, and most tropical cyclones occur from late June to early October.
Based on a 30-year climate period from 1991 to 2020, an average eastern Pacific hurricane season has 15 named storms, eight hurricanes and four major hurricanes. The first named storm typically forms in early to mid-June, the first hurricane tends to form in late June, and the first major hurricane forms in mid-July.
Will the 2023 hurricane season be active?
Forecasters, in general, predict a near- to slightly below-average year for hurricanes in the Atlantic. That's in part because of the influence of an expected El Niño, which tends to reduce Atlantic hurricane activity.
Top forecasters from Colorado State University predict that 13 tropical storms will form in the Atlantic, of which six will become hurricanes.
But El Niño tends to boost hurricane activity in the eastern Pacific basin, so the west coast of Mexico could see an unusually active season.
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Contributing: National Oceanic Atmospheric Administration; National Hurricane Center