Cold Index
The "common cold" is one of the most pervasive illnesses, affecting most people several times each year. There are more than 100 different viruses that cause colds and there is no known cure except time. Most colds are transmitted through either direct contact or close proximity to an infected person.

The weather plays several important roles in the chances you will get a cold and, if you do, how severe it will be and how long it will last. These factors are combined to yield the proprietary Cold Index, with higher index numbers meaning the chances of catching a cold and having it last longer are higher.