Also bear in mind that if your station is set up in a locale with more vegetation (i.e. trees, shrubs, irrigated grass, etc.) such as a neighborhood/subdivision than at an open and exposed location like an airport/airfield, you will have a lot more transpiration of water vapor from the vegetation leading to locally higher vapor pressure, relative humidity, dewpoint, etc. With this considered, air with a higher water vapor content heats less efficiently than air with lower water vapor content. So there may very well be discrepancies this manner as well.