Probably double conversion error which is common. Station reports whole °F which gets turned into tenths of °C for the METAR T-group, then web sites take the tenths of °C and translate that into tenths of °F. Station reports 87°F which is encoded as T0306xxxx in the METAR then some web site converts the 30.6°C to 87.1°F. You can always tell when this is happening because the tenths of degrees are always .8, .9, .1, or .2.