Be wary of attic vents, window reflections, asphalt, or anything that is in direct sunlight and near the sensor. My readings aren't quite what I expected them to be. Be very careful. Comparing to readings obtained from the television, radio, newspaper, or a neighbor is not the most accurate method of verifying your readings. We test the weather stations carefully at our factory to conform to the specifications listed in the back of your manual.
Relative humidity is a percentage of total air saturation by water vapor.
When the temperature increases the percentage of total air saturation decreases and vice versa. Dew point is the temperature at which the air becomes saturated with water vapor. Its value is calculated using outside temperature and outside humidity.