|MadSci Network: Earth Sciences|
Prior to the age of scientific inquiry and instrumentation, knowledge of weather was based on experience at a particular location...and passed down from generation to generation. This knowledge was based on the climatology of the seasons and supplemented with personal experience. Forecasts as we know them today didn't exist. Short term forecasts were based on the deviation from normally expected conditions, say wind shifts, cloud changes, or temperature drops and rises, at a given location.
Try the links in the MadSci Library for more information on Earth Sciences.