In a few hours, Hurricane Harvey is likely to hit Corpus Christi, Texas. Much of the area will quickly lose power, and perhaps drinking water, too. On the coast, there will be a storm surge, and on top of that the storm will dump rain, too—perhaps 35 inches, though more probably 15 to 25. Even on the lower side of that range, “rainfall of this magnitude will cause catastrophic and life-threatening flooding,” according to NOAA. “The time to evacuate and heed the warning is quickly coming to a close,” Brock Long, the administrator of the Federal Emergency Management Agency, said on MSNBC Friday.

So why is anyone still sitting at home in the storm’s path?

“Whenever you stay with a storm, it’s a crapshoot,” James R. Jones told me Friday afternoon from his boarded-up Corpus Christi home. “I’m looking at the data myself, so that’s why I’m still here.”

Jones is unusual in some respects: A retired science teacher with a master’s degree in earth sciences, he knows more about hurricanes than most citizens. He is also fairly well prepared, with water, a radio, a stove, and flashlight at the ready, and his house is boarded up. His garage has a hurricane-rated door, and his house is flood-insured.

In other ways, though, he is fairly typical. Even with major storms bearing down, many people decide they’d prefer to stay in their homes. The reasons for this vary: Some people judge themselves able to weather whatever comes their way. Others are simply physically unable to evacuate. Sometimes they’ve lived through past storms and figure that if they’d made it through those they can take one more. Overall, the challenge is that hurricanes represent a high-risk, low-probability event, and some are inclined to bet that things won’t be that bad.

It’s hard to say what a “normal” percentage of residents to stick around is: Every storm is different, and more powerful storms tend to produce higher rates of evacuation, as do mandatory evacuation orders. The number of people who decide to stay may vary by region, too.

Although the residents of some low-lying areas in Harvey’s path have been ordered to evacuate, Corpus Christi as a whole has a voluntary evacuation order in place instead. “We could mandate it, but people need to make a decision of their own,” Mayor Joe McComb said Thursday. “I'm not going to risk our police and fire people going to try and drag somebody out of the house if they don't want to go.”

So Jones made his decision, and he decided to stay. For one thing, he’s betting Harvey will either miss Corpus Christi or come in a little weaker than the Category 3 storm some forecasts predict. He has also weathered storms in the area before. In 1980, Hurricane Allen dropped in power right before landfall. The reverse happened with Hurricane Brett in 1998: The storm got more powerful at the last minute, and Jones had to pull an all-nighter cutting wood and boarding up windows.

“If I had young children I would leave. If my wife was here I’d probably leave, but she’s not,” he said. By now, he figures the roads would be too clogged to effectively leave anyway. Besides, he feels an obligation to look out for his neighbors, many of whom are older and less mobile. He’s spent the last few days helping board up their houses. “I’m 66 and I’m in very, very good shape. Some of these people are not. The people on either side of me may need some help, and they really can’t leave.”

Older people, people with smaller social networks, and those who are less well-off, are more likely to stay put in a storm. These people worry emergency planners. Disaster experts agonize in particular over those who don’t understand what storms are likely to be like and don’t have a disaster-readiness kit like the ones Jones does, so on that count he’s way ahead. It’s the easiest way to prepare for any disaster, from a hurricane to a house fire, and yet many people don’t do it.

Whether they have a kit together or not, people’s memories of past storms tend to play a major role in decisions about whether to leave. That cuts two ways: New residents in a hurricane zone might not know what they’re in for; veterans tend to remember prior storms and assume that things won’t get any worse.

“Somebody in emergency management in Mississippi told me after Katrina that the thing that killed the most people from Katrina was Hurricane Camille in 1969,” Russ Paulsen, then-executive director of community preparedness and resilience services at the American Red Cross, told me in 2015. “People remembered that whatever they did kept them safe, so they did it again. Only this time, there was a much bigger storm surge. Those people who were okay from a mostly-wind event in 1969 were not okay when there was 30 feet of water coming at them.”

The challenge for emergency managers is that sometimes storms really do dissipate before hitting land, or they turn away and do less damage than expected. Since the actual severity and direction of a storm are subject to change, authorities have to get people to prepare for the worst even as they know it sometimes won’t happen. There’s a risk that successive warnings will just numb people to the danger. But there will also be residents who understand the risks and decide to go with it.

“It’s a chance I’m taking,” Jones told me. “I can’t say that this is a totally safe thing to do, because it’s not. But it’s a decision I’ve made. I’m as prepared as I can be.”

All that was left, he said, was to watch the Weather Channel and wait to see how his gamble paid off.