A weather map provides a view of weather elements over a specified geographical area at a specified time. It is obtained by plotting or tracing the values of relevant quantities such as pressure, temperature, cloud cover, and others, onto a geographical map. The data can be either measurements or forecasted values.
The use of weather charts in a modern sense began in the second half of the nineteenth century as telegraph made it possible to gather weather information from multiple distant locations quickly enough to preserve its value for real-time applications. More recently, advances in both the fields of meteorology and Geographic Information Systems have made it possible to devise finely tailored products that take us from the traditional weather map into an entirely new realm. Weather information can quickly be matched to relevant geographical detail. For instance, icing conditions can be mapped onto the road network.