My opinion is that 100-year averages are the minimum ... we'll get a better understanding of Earth's climates using 1,000-year averages ... in the context of our ten-million-year averages ...
The idea of averaging is to remove some of these daily and seasonal differences when we compare one year to the next ... and these yearly averages are themselves quite variable ... as you point out, some winters are way way below average in temperature ... remember the Space Shuttle Challenger ... that was 25ºF polar air there on the launch pad on Cape Kennedy ...
Bad weather happens ...
I ask how many hurricanes have landed in Miami these past 10,000 years? ... yes, I know ... that's because getting hit with hurricanes is part of Miami's climate ... no change needed to be hit with another ... and she will get hit with another ... that's the same climate ... I'm sorry, the cause of Iowa's summer rains isn't temperature ... Meteorology 201 ... we'll just see longer growing seasons ... and we both know how bad that is for farmers ...