7 Things You Don't Know About Colds

While winter colds are usually gone after a few days, their summer cousins can stick around for weeks. This is partially due to the fact that they're caused by different germs. Rhinoviruses and some other cold-causing viruses survive best in cooler weather, while the enterovirus seems to thrive from June to October. Some experts believe that another reason summer colds persist is that we're more likely to do things in warm weather (blast the air-conditioning, which can dry out the protective lining of your nostrils, try to "sweat out" the cold by over-exercising, refuse to go to bed early) that make it harder for our immune system to fight them off.