Jwing: In a word, no. There is a lot of circumstantial evidence that suggests a link to climate variations, such as the Little Ice Age in the 1600s corresponding to the last grand minimum of no sunspots, as well as the Medieval Warm Period corresponding to a period of suspected high sunspot activity around the year 1000. Our knowledge of the Sun’s brightness variations however remains somewhat limited, and so we do not know yet.

LocalFluff: The sunspot number isn’t the equivalent of a count of actual sunspots. See for example this page: The sunspot count for today is 22, even though only 2 sunspots are visible on the face of the Sun.

Solar scientists use a complex algorithm to calculate the number based on the number of spots visible. Don’t ask me to explain it, but it really doesn’t matter, as the system has been used pretty much consistently for more than a century.

LocalFluff: You appear to be misreading the graphs. The longer-term graph shows average monthly values, not the day to day sunspot numbers. The 2017 graph only covers most of January 2017 and the first week of February 2017, and shows the actual count for each day. That’s why the 70 count in January on the 2017 graph does appear on the longer term graph.

In addition, the two graphs use a slightly different definition of sunspot numbers, so while their numbers might differ a little bit, they are relatively identical so that the line of the graphs when plotted for the same time period will be practically the same.

The Sun’s differential surface rotation, varying from 25 days at the equator to 35 days at its polar regions messes up any periodicity on a monthly time scale. So called butterfly diagrams illustrate how sunspots migrate, or are formed and ceased, systematically along their latitude, during a sunspot cycle period because of that differential rotation.