The Collaborative International Dictionary of English v.0.48:

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.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

weather map
    n 1: (meteorology) a map showing the principal meteorological
         elements at a given time and over an extended region [syn:
         weather map, weather chart]

Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "weather map":
   Lambert conformal projection, Mercator projection,
   Miller projection, aeronautical chart, air mass, anticyclone,
   astronomical chart, atlas, azimuthal equidistant projection,
   azimuthal projection, cartographer, cartography, celestial chart,
   celestial globe, chart, chorographer, chorography, climatic chart,
   cold front, cold sector, conic projection, contour line,
   contour map, cyclone, cylindrical projection, front,
   general reference map, globe, gnomonic projection, graphic scale,
   grid line, hachure, heliographic chart, high, high-pressure area,
   hydrographic chart, index, isobar, isoline, isometric,
   isometric line, isopiestic line, isotherm, isothermal line,
   latitude, layer tint, legend, longitude, low, low-pressure area,
   map, map maker, map projection, mapper, meridian, occluded front,
   parallel, photogrammetrist, photogrammetry, photomap,
   phototopography, physical map, polar front, political map,
   polyconic projection, projection, relief map,
   representative fraction, road map, scale, sinusoidal projection,
   special map, squall line, stationary front, terrain map,
   terrestrial globe, thematic map, topographer, topographic chart,
   topography, transportation map, warm front, weather chart,
   wind-shift line