September is historically the peak month for Atlantic Ocean hurricanes, but it’s understandable if you’ve forgotten that. The last hurricane to threaten the U.S. in September was Hurricane Ike in 2008.

In many ways, we’ve been “lucky” since the mid-2000s. Florida has not been hit by a hurricane in 10 years; its previous record for longest hurricane-free streak (dating to the 1850s) was five years. It’s also been almost 10 years since the last major hurricane — Category 3 or higher — struck the U.S. (Wilma, the fifth-costliest hurricane in U.S. history, in 2005).

But there’s a downside to those years of good weather. While the big storms have stayed away, the coastal population in the U.S. has continued to increase, and in a few cases it has been surging. When a major hurricane next strikes — and it will — it will very likely hit an area that is even more vulnerable to destruction, with a large group of new residents who might have no experience with extremes of high winds and water.

I moved to Houston in 2012, one of more than 800,000 people to do so since 2008, when Hurricane Ike hit the area. According to the Houston-Galveston Area Council, the population of that eight-county area is expected to grow more than 40 percent through 2040 to more than 10 million people. A list published by the Greater Baton Rouge Industry Alliance earlier this year showed more than $100 billion in industrial projects proposed or underway in Louisiana. Although there are always risks because of fluctuations in oil and natural gas prices, the bottom line here is that the Gulf Coast is in the midst of a tremendous economic boom.

The combined populations of the Gulf Coast Metropolitan Statistical Areas (MSAs) have grown by 12.2 percent, or 1.8 million, since they were all last directly affected by a hurricane. It’s tough to determine how much of the new coastal population has never experienced a hurricane, but we know the number is probably substantial. We also can’t say for sure whether people who have never experienced a hurricane are more or less likely to follow recommendations for evacuation when one is expected to hit.

The population growth of the Atlantic Coast has also been considerable, especially in the Southeast.

The Jacksonville area in Florida is arguably the least experienced with hurricanes among cities in the region, as its last hurricane was David back in 1979. Nearly 700,000 people have moved to that region since. Fortunately, the area from Jacksonville north to Savannah, Georgia, occupies a concave coastline that often acts as a natural safe harbor from hurricanes. Many storms miss them to the east as they move north toward North Carolina and New England or go out to sea. Alternatively, they also often stay south and go into central and south Florida. That doesn’t mean hurricanes don’t hit Jacksonville and Savannah; they’ve been hit before, and they will be hit again.

Miami was last hit by Katrina and Wilma in 2005. Since then, more than half a million people have moved to the region. Scarier yet, since the devastating blow delivered by Hurricane Andrew in 1992, more than 1.6 million new residents have settled in Southeast Florida.

Farther up the coast, the region between Brunswick, Georgia, and Wilmington, North Carolina, has added more than 420,000 new residents. Metropolitan New York City has added more than 200,000 residents since Sandy, but only about 28,000 of them live on Long Island or in the coastal counties in central and northern New Jersey. Although Boston sees more strong non-tropical storms than many other locations, a large number of residents have moved there since Hurricane Bob struck in 1991 and have never experienced a true hurricane.

“It’s not a simple problem,” said Rebecca Jennings, a Federal Emergency Management Agency (FEMA) meteorologist, noting that hurricanes are more than “just a point on a map.” Some new residents may not fully accept the hazards of “just” a tropical storm or Category 1 or 2 hurricane and refuse to obey evacuation orders or other official advice, even though those hazards can include flooding, tornadoes or strong winds well inland. “Many new coastal residents may be generally aware they now live in ‘hurricane country,’ but the concern is they may underestimate their true risk,” she said.

Official warnings may be more likely to be disregarded as new residents see hurricanes bypass their areas year after year. But the moderate weather we’re experiencing is, in historical terms, quite rare. According to Phil Klotzbach, a hurricane expert at Colorado State University, 29 percent of all major hurricanes recorded from 1900 through 2000 affected the U.S. But last month, Hurricane Danny became the 26th consecutive major Atlantic hurricane to miss the U.S. Per Klotzbach’s numbers, the odds of that are 1 in 7,400.

Although hurricane hits in this country have been down, major hurricanes have struck the Caribbean and Mexico at normal or greater than normal frequency since 2005. Studies have concluded that it’s simply “dumb luck” that the U.S. has not been hit by a major hurricane since 2005. The scientist side of me wants to argue that there has to be some sort of meteorological reason for it (cyclical weather pattern differences, climate change, etc.), because globally, accumulated cyclone energy is down in recent years (2015 has seen a dramatic spike in Pacific Ocean tropical activity, likely due in part to El Nino, that has helped bring it back up). But as of yet, we simply don’t have a definitive scientific explanation, and perhaps ultimately it is just good fortune.

But as Jennings says, “That luck will run out. It’s really a matter of where and when at this point.” And she and other experts are worried about what will happen when it does.

“I hope we are not being lulled into complacency by our recent luck,” says Jamie Mitchem, a professor, meteorologist and researcher at the Institute for Environmental & Spatial Analysis at the University of North Georgia who has studied social vulnerability to disasters.

The key is making sure that all residents, new and old, understand those risks and prepare ahead of time.

“We need to find a way for people to make (preparing) a habit, not just right before or after they need it,” Jennings says. One suggestion is to have good, legitimate sources of data bookmarked today. Following the National Hurricane Center, a National Weather Service office, and good local sources of information such as a local emergency management office or local broadcast meteorologists will ensure that hurricane-prone residents have reliable information quickly accessible.

When a storm does threaten, it’s vital for residents to listen to their state and local officials, Jennings said. Meteorologists such as Jennings, along with many organizations, work with state and local officials to ensure that evacuation zones are backed up by good data and sound science. “Don’t try to outguess the experts. If you’re ordered to evacuate, go,” Jennings says.

Tampa, Florida, was affected by hurricanes in 2004 and 2005 but hasn’t been directly hit since Hurricane Gladys in 1968; it has nonetheless done a good job of information prep. Jennings praised the surrounding Pinellas County for the quality of its online resources for residents, adding that FEMA and the National Hurricane Center spend a substantial amount of time in the “offseason” working with state and local emergency officials in the region to prepare and implement hurricane plans.

Whatever you want to call this hurricane-free streak, it will end at some point. If you’re one of the many to now call the coast your home, it would be wise to prepare for the day it does.

CLARIFICATION (Sept. 24, 9:50 a.m.): The language in this article has been updated to reflect that although global accumulated cyclone energy is down, there has been a spike in 2015 in Pacific Ocean tropical activity.