Source : Webster's Revised Unabridged Dictionary (1913)

Weather map \Weath"er map\
   A map or chart showing the principal meteorological elements
   at a given hour and over an extended region. Such maps
   usually show the height of the barometer, the temperature of
   the air, the relative humidity, the state of the weather, and
   the direction and velocity of the wind. Isobars and isotherms
   outline the general distribution of temperature and pressure,
   while shaded areas indicate the sections over which rain has
   just fallen. Other lines inclose areas where the temperature
   has fallen or risen markedly. In tabular form are shown
   changes of pressure and of temperature, maximum and minimum
   temperatures, and total rain for each weather station since
   the last issue, usually 12 hours.

Source : WordNet®

weather map
     n : a map showing the principal meteorological elements at a
         given time and over an extended region [syn: {weather
         chart}]