Hi,, can anyone help me with my old worlds weather? I updated my world from 1.7.3,,, to RC2. My world had a massive snow biome right at the spawn point and now it jus rains everywhere, even in the snowy area?

Ive had this world since 1.3 and theres alot of work in the world,, Ive searched all over the net and theres nothing on this matter,,