When you're calling or listening on the radio, you aren't getting a METAR, you're directly accessing the ASOS/AWOS/etc.
True, but I believe the automated METARs are accessing data from the same system, and this introduces a little confusion about winds.
I was taught that METAR and TAF reports give wind in degrees true, whereas ASOS/AWOS give degrees magnetic. ("If it's written it's true," goes the saying) But this doesn't seem to be the case. I can look at my airport's METAR online while I'm listening to the AWOS and get the same number for wind direction. I'm guessing both are magnetic, but can't be 100% certain.
I really wish that METARs and TAFs would introduce the letter T or M to resolve any confusion, so wind direction would be written "270T" or "270M".
Better yet, just make all airport reporting in degrees magnetic. It makes sense to me that airport data should always be in degrees magnetic (TAF and METAR and AWOS/ASOS), since runway numbers are magnetic. I don't know why we'd ever give such in degrees true. For winds aloft, true makes more sense as the wind report might span different magnetic variation regions.