The first thing about reading weather maps is understanding which direction air masses move.

Physics laws show that gases move from high pressure to low pressure and weather systems also follow this. This is what causes weather to move in and out of areas, like when weather forecasters often say things like "a low pressure system is moving in".

On maps, there are ways of showing where the high pressure systems are, so that we can tell which direction weather will move (towards the lower pressure area). Curvy lines on weather maps show pressure measurements, and by reading the pressure lines (called isobars) we can say that the weather system will move towards the lower pressure number. Sometimes the weather forecaster will add little triangles or arrows to show the direction the weather is traveling on the map.