Sunny is a Virgo
Cirrus is a Gemini
Sky - I'm not sure about but since I adopted him on June 7th that's his b-day and it really fits his personality so he's another Gemini.
Storm- I don't know his actual b-day either but I adopted him on Jan. 11th so he's a Capricorn.

My RB Pepper's b-day was March 17th so he was a Pisces and this fit him too. He also had liver problems.