The North Atlantic Oscillation (NAO) is considered a key driver of winter weather patterns over the northern hemisphere. A positive NAO is linked with more windstorms, and mild and wet winters in Europe. A negative NAO indicates snowy and cold winters in Europe. In recent years, published research has claimed the existence of a correlation between the NAO and the 11-year solar cycle, a periodic change in the sun’s activity. That theory has held that the connection between the NAO and the solar cycle is strong enough to inform predictions of the NAO as much as a decade in advance, which would in turn, enable scientists to predict winter weather patterns as many as ten years in advance.