NEW YORK (CBSNewYork) — Remember what your mother always told you? Put a coat on or you’ll catch a cold in this weather.

But doctors have always told us cold temperatures don’t cause colds — viruses cause colds.

Now, as CBS2’s Dr. Max Gomez reported, mom may have been right all along, sort of.

Funny how mom’s advice often turns out to have some truth to it.

A new study from Yale University found that cold temperatures really can lead to colds, but not for the reason you might think.

As the thermometer drops and the weather gets miserable, cold and flu rates jump. But why?

Doctors have always said it’s because we understandably want to stay indoors during cold weather, in much closer contact with other, possibly sick people than we normally would in the summer.

But the real cause?

“The common cold is still caused by a variety of different viruses, most common the Rhinovirus,” said Dr. Roberto Posada, with Mt. Sinai Hospital.

But nevermind science, people still believe it’s the weather that causes colds.

“If you don’t dress properly for it and you’re out in the cold for a while, it’s hard on your system,” said Manhattan resident Emily Schorr.

Well now, science may back up the common wisdom. A study in the Proceedings of the National Academy of Sciences found that cold weather may actually make it easier for viruses to invade.

“The immune system is less able to protect itself from the virus at cold temperatures,” said Dr. Posada. “The cold temperature that is present in the nose compared to the lungs where the area is a little bit warmer.”

Turns out certain cells in the body secrete chemicals that help ward off infection from germs like cold viruses.

But at the temperatures in the nose, especially when breathing cold air, those cells can’t churn out as much protective substances. So viruses find it easier to infect.

Wearing a scarf around your face might warm your nasal cells a bit, but it’s not known if that’s enough to ward off colds.

One thing it might do though, is ward off asthma attacks.

“Cold air can trigger asthma, but also could be related to the drier air in winter,” Dr. Posada said.

That dry air also impairs the germ barriers in the nose, again making it easier for viruses to get in.

The best way to avoid catching a cold in the winter is still the old-fashioned way: washing your hands early and often.

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