Here's a cold, hard fact: No matter how long you live in South Florida, your blood will not thin out and make you sensitive to chilly weather.
On the one hand, if you move from a cold to a warm climate, you might lose some fat because your body will no longer need as much insulation. You also will be less prone to get the winter blahs because of all the sunshine in these parts — yet that sunshine also can increase your chance of contracting skin cancer.
You'll be more likely to develop sinus problems because of all the air conditioning in South Florida homes and buildings. And, if you're one of those who leaves the windows open, you might not sleep as well in the subtropical heat.
Thinner blood, however, "is absolutely a myth," said Dr. Bruce Lenes, medical director of Community Blood Centers of South Florida, noting that blood thickness isn't influenced by temperature. He said people simply adjust — mentally and physically — to a new climate.
"It's just a matter of getting used to the warm," he said.
Martin Zenor, of Boca Raton, said when he moved to South Florida 16 years ago, he used to wear T-shirts and shorts in the winter, even when it was cool outside.
"Now I bundle up with layers if it gets colder than 60," said Zenor, who grew up in Iowa. "I complain about the cold to family and co-workers, particularly this winter and last winter."
It's forecast to get cold again Saturday night and Sunday morning, with temperatures falling into the mid- to upper 40s. But it should be short-lived, with near-normal readings Monday and Tuesday.
While warmer temperatures don't thin out blood, living at high altitude does, Lenes said. That allows people who live in the mountains to function with less oxygen in their blood.
Otherwise, the only other physiological change of moving to a warm climate is that people tend to lose fat, a process that takes a couple of years, said Dr. Charles Rouault, president of Community Blood Centers of South Florida.
Conversely, he said, mammals that live in arctic regions develop a layer of fat to insulate against the cold. The fat is created when cold prompts estrogen to bind with fat cells, which then multiply.
"That's why whales and walruses are fat," he said.
Blood aside, people usually sleep better in cooler temperatures. The reason: The body's temperature decreases in sleep, and a cool room aids that process, experts say.
"In cold temperatures, our metabolism slows," said Ken Kronheim, a licensed therapist and a Broward Sheriff's Office assistant fire chief who has researched what hurts and helps sleep. "Basically our physiological tendencies slow down."
All told, South Florida's warm climate promotes good health, as good weather allows people to play and exercise outdoors, authorities say.
It also might help those with seasonal affective disorder, also thought of as the winter blues. The disorder is actually a form of depression linked to a lack of natural light. For that reason, the disorder is much more common in arctic regions than in sunny places like Florida.
"The darker and colder it is, the more likely it is to cause depression," Kronheim said.
Yet, there are several maladies associated with moving to a subtropical climate, said Dr. Robert Schwartz, professor and chairman of the Department of Family Medicine & Community Health at the University of Miami.
High among them is an increased risk of skin cancer. "People in South Florida tend to be outdoors more than those in the North, and they don't always protect themselves," he said.
According to the Centers for Disease Control and Prevention, Florida's skin cancer rate is about equal to the national average of 18.7 people per 100,000 who develop or die from the disease each year.
No matter what the temperature is outside, people are vulnerable to the sun's rays, experts note. To prevent skin cancer, they recommend avoiding sun between 10 a.m. and 4 p.m.; wearing hats and long-sleeved shirts made of tightly woven fabrics, as well as sunglasses; and liberally applying sunscreen with SPF 15 or higher.
Sinus problems are common in South Florida because so many buildings have air conditioning, which not only makes air cold but also dry. Dry air irritates nasal passages and can lead to sinus infections.
"And then there's the problem of mold," which also can aggravate sinus problems and allergies, Schwartz added.
For many in South Florida, winter's cooler weather is simply a nice break. They can shut off the air conditioning and don sweaters, hats and other clothes they wouldn't normally wear, Kronheim said.
But he said most people have a limit to how much cold they can take.
"Even someone who loves cold weather, after the third or fourth day of it, they want the warm weather back," Kronheim said. "I know I do."