Keeping Radio Equipment Cool?

Does anyone have suggestions on how to keep roof-top radio equipment 
cool?  I have three Net Nimble WRIP's.  Two of them I use as relays.  
The problem that I have been having is they lock up in the heat.  It 
has been getting about 103 here and could get hotter.  I need to find a 
way to keep the electronics cool and also keep them sealed from the 
dust, dirt, and sand.

Any suggestions?

Thanks!