The task of predicting the weather that will be observed at a future time is called weather forecasting. As one of the primary objectives of the science of meteorology, weather forecasting has depended critically on the scientific and technological advances in meteorology that have taken place since the latter half of the 19th century.Throughout most of history, forecasting efforts at any given site depended solely on observations that could be made at that site.
Observations of sky, wind, and temperature conditions and a knowledge of local climate history permitted a limited predictive ability. Weather lore was also accumulated in an effort to codify apparent patterns in the behavior of the atmosphere.With the development of the telegraph in the mid-1800s, weather forecasters were able to obtain observations from many distant locations within a few hours of the collection of such data. These data could then be organized into so-called synoptic weather charts, synoptic meaning the display of weather data occurring at the same time over an area.
These were the predecessors of the synoptic weather maps produced today. The physical bases of atmospheric motions were not yet understood, however, so prediction depended on various empirical rules. The most fundamental rules developed in that period were that weather systems move and that precipitation typically is associated with regions of low atmospheric pressure.