User blog comment:Xilinoc/Ch. 567 (Rukia be like "I ain't even scared though")/@comment-11721917-20140206050355/@comment-24282510-20140206050726

"If she could control the temperature, then she could also raise it, right?"

Not unless her zanpukto is a dual fire and ice type (which would be nice) but zanpuktos are limited to 1 type. So no she can't unless you count her returning to her normal body has raising it.