Here’s what you need to know.

By Taylor Eisenhauer

Hurricanes Florence, Helene, and Isaac are all currently brewing in the Atlantic Ocean. This is the eleventh year on record that the Atlantic has had three or more named storms simultaneously.

Florence has strengthened into a Category 4 hurricane and is expected to make landfall in the southeastern U.S. by Friday. North and South Carolina and Virginia have already declared states of emergency, and officials have begun evacuations in North Carolina.

RELATED: 'Extremely Dangerous' Florence On Track to Hit East Coast As Major Hurricane

The National Hurricane Center (NHC) warns that swells are likely to cause “life-threatening surf and rip current conditions.”

Helene, which formed as a tropical storm last Friday night, is heading toward the Cabo Verde islands off the eastern coast of Africa, while Isaac is moving west toward the Caribbean, including the islands of St. Lucia, Dominica, Martinique, and Grenada.

NHC forecaster Chuck Caracozza notes it’s not unusual to track three or more storms this time of year. “It’s the peak of the hurricane season, so this is definitely the time,” he says.

This happened last year, too, when Hurricane Jose and Tropical Storms Maria and Lee were churning at the same time. Here are all 11 years on record that the Atlantic has hosted three or more named storms: 1893, 1926, 1950, 1961, 1967, 1980, 1995, 1998, 2010, 2017, and 2018.

According to the NHC, there is a chance that the Atlantic could have as many as five concurrent named storms in the next five days. The previous record for active simultaneous storms is four, which has occurred several times in the past.

Before hurricane season ends on November 30, the National Oceanic and Atmospheric Administration (NOAA) expects a total of nine to 13 named storms.