Wondering who's going to beat August now. Before Irene came along, I was guessing Erza would fight him, because reasons. Now Erza seems to be 120% set on fighting Irene because Plot, so that leaves August without a legitimate opponent. And Natsu can't fight him since he already has Jacob and is inevitably going to fight Zeref again.
Regarding Irene's power, it's got to be more than just weather control. My guess is that something to do with the the sun and the moon, or Day and night, since her Fangirls have a clear Sun and Moon motif going on. When she made the snow vanish, she amplified the power of the sun. It sounds horrendously broken, and would need some kind of friendship power up to beat.
Other possibility, Season manipulation. She turned winter into Spring. This gives her access to all sorts of crazy possible powers. Temperature Manipulation, though that seems more like a Natsu enemy. Just a good Meteorologist: Always a possibility.