Then you get a station like BVY that is on the water like BOS. Other than some bad data that got repaired here and there, their temps have been fairly consistent over the last 6 years. If the BOS jump was somewhat real, you'd expect to see similar errors at BVY.
I remember when we saw the CON numbers creeping up and Chris found they had installed rocks around the ASOS for better maintenance. Now their numbers are back in line. Goes to show you how much the surface around the sensor suite has an effect on the readings. I honestly trust Davis FARS readings more than some of the ASOS sites now. They may have 0.01C accuracy, but it doesn't mean much when they're measuring over rocks, sand, or concrete and averaging the data over 5 minutes. The days of yore probably have 12" tall grass around a stevenson screen with mercury max/min thermometers.