Maybe this is why its scorching hot here. I need some Letty to even things out.
(also I tagged sunbursts as Im pretty sure it qualifies here but correct me if it should be sunbeams)
Letty doesn't create cold like Cirno does, she can only manipulate cold that's already there. If it's hot, she loses her power and goes into hibernation until winter comes again.
I'd say get Cirno in here instead, but she'd probably melt.