I found this topic after searching in google 'warm weather helps acne'.
Pretty much every result talked about warm weather causing more acne, oddly, for me, it's the opposite.
I've lived in a cold rainy northern climate all my life, and had acne all my life, but every time I go away to somewhere warm, my skin gives me no trouble at all, it basically completely clears up.
I've just moved to Thailand and from day 1 my skin started to look and feel better. Acne that was beginning to form and 'bubble up' during the 20 hour journey to get here totally cleared away within 24 hours of arriving in Thailand.