You're implying that the error is always going to be slight. Secondly, you're using a prediction as an example rather than hard data.

What I would like to see is the correct data. People don't always have to predict the weather, but they should be diligent enough that if they want to prove someone that the weather a year ago was different than what sources say, they should have the right numbers in front of them

So if the CDC numbers aren't the truth, and the image OP posted is not the truth, then that doesn't get us anywhere