As we head through fall and into winter, the importance of two oscillations in the Northern hemisphere increase dramatically. Namely, the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) are monitored carefully mostly for the affects they have on the temperature and storm track over the US. Basically, if the phase of both indices are negative, colder than normal air is allowed to flow into the Northeast from the arctic and a stormy track (and snow) is favored along the Eastern Seaboard.
So what does the sun have to do with all of this? Well, for reasons not fully understood by the scientific community, it seems that low solar activity (the lack of sunspots) is roughly correlated with the negative phase of the AO and NAO. The reverse is also true, with high solar activity (many sunspots) associated with the positive (warmer) phase of the oscillations.
Interestingly, since the 1990 sunspot maximum, each successive ~11 year peak has been declining in strength. 2013 marks the most recent solar maximum and it has been rather lackluster seen below:
In fact, if we have peaked (which is the general consensus) this will mark the lowest peak in 100 years. Some scientists also believe the low activity trend will continue into the next solar cycle or even (more extremely) the next solar maximum may be skipped all together. This is not as crazy as it sounds, it has happened before as seen in the historical sunspot graph below:
In fact during the "Maunder Minimum" (starting in 1650) the Earth was in a period called the "Little Ice Age", which after a brief break in the early 1700's returned during the "Dalton Minimum" from 1790 - 1830. During the Little Ice Age, New York Harbor froze and people even walked from Manhattan to Staten Island on the ice! While solar activity was not the only cause to the Little Ice Age (some say volcanic activity and orbital cycles contributed too), it's interesting the cold period coincided with the sunspot minimum.
While something as drastic as the Maunder Minimum and Little Ice Age is rather unlikely in the coming years, it is important to remember that this current low solar activity trend may lead to more frequent negative phases of the AO and NAO. From earlier, this more persistent negative phase MAY lead to colder and stormier winters over the next 20 years or so. On the other hand, could human initiated global warming negate any overall cooling effects from this hypothesis? We'll need to wait and see.
