Could you be more specific? There are at least two possible answers.
On radar map, different colors are used to indicate rain / snow intensity. In this luggage, light blue is desk light rain, green is a bit heavier rainfall, yellow is fairly heavy precipitation, and so on.
The other possibility is to indicate areas of like heat.
Please include a link to an example weather map so I can see what you indicate.
orange method a very strong storm and stout rain red even system stronger yet green is the lightest white is snow blue is sleet Color Intensity Description
Blue Light hurricane lantern rain or snow
Green Heavy reading light thunderstorms/moderate rain showers
Yellow Very Heavy moderate thunderstorms
Red Intense potential flooding rains/severe thunderstorms
Magenta Extreme flooding rain Source(s):