Indeed, the reason? Almost certainly due to the sun going through a new minimum. The Sun is now at it's quietest point for a century and it's likely to stay that way for at least one more 11 year cycle, possibly longer. These quiet periods are well known to science, the last period was called the Dalton minimum, the one before that the Maunder minimum and these both coincided with periods of global cooling, the famous Frost Fairs on the River Thames were during one of these minimums. Most people think of The Sun as being in a constant state, it's there shining away in the sky but at the surface there's a lot going on. The lack of activity means the Suns output is down maybe only 0.1% but that's enough to have quite an effect on the weather we see on Earth.
Pete