Play or sing a few songs about the weather. Good examples include "You are my Sunsine" and 'Its Raining, its Pouring."
Create simple icons (draw them on the chalkboard) such as a white cloud for cloudy days, a black cloud for days in which it might rain, etc.Then, discuss weather reports on television with the students. What kinds of things do the reporters say? What types of pictures does the television show during weather reports?
Watch actual weather reports in class, if possible. Also, look at weather maps from the newspaper and talk about what the different symbols mean.
Give students time to draw their own weather pictures. There is no right or wrong at this point, the key is to tap into their individual creativity.