I have the same problem. Today my curls were so blah....(rain and 57)...yesterday (sunny and 80) they rocked.
Do you add more moisture to your hair in the winter? Or less?
3a/3b normal porosity & density. Curly Girl since August of 2012
Co-wash: Suave Naturals Coconut
Rinse Out: GVP Conditioning Balm
Leave In: (Still working on it...right now using a small amount of Deva Care "One Condition")
Styling: Curl Keeper, Jessicurl Rockiní Ringlets, DevaCurl Styling Creme, and Arc AnGell