Outlier is a term that should be reserved for obviously wrong data - for example, if St. Louis had an average temp of 54F on one thermometer for one day and another thermometer one mile away had 40F degrees, both are suspect; while if one out of ten in a close radius differ where only one was off by more than one degree the spurious one becomes obvious.
Move out beyond ten miles and narrow your time allowed to ten minutes and that one thermometer becomes a predictor.
I rechecked St. Louis for February, 2008 and it was warmer than 2007 by 1C, but not 3C.
That's fine, but raw data can have outliers. Something has to be done about them.
I rechecked St. Louis for February, 2008 and it was warmer than 2007 by 1C, but not 3C.
But St. Louis doesn't account for the whole dot.
The plot is for January; eyeballing the one closer to St. Louis, it looks more like 2C than 3C, size-wize. There must be a text presentation of the data somewhere, but I don’t have time to look for it.