Yesterday it rained;

today the sun is shining -

   That's just how life goes.

             or

     But life still goes on.

             or 

     Life is like that - No?

 

 Ok, a couple of things.  

+Actually that's just turned around - yesterday was sunny, after a few sprinkles, and today it is raining, as forecast!  

+And then what I was trying to get at here is not that it rains and then the sun shines and then it rains, etc., but rather that life has it's ups and downs just like the weather changes.  So I think I like the second last line best.