I'm gone for the weekend, but if cold is a contributing factor in his medical issues, Kitten can manage to heat air to something less than fire-temperature. I'm sure she could handle comfortably warm, with no flames involved in summoning it up. She can also probably dry him off with a spell.

(She will be already be hiding below deck wishing she could DO something but knowing she'd be more of a hindrance than a help given she can't swim, can't scale rigging as easily, isn't that strong, etc. She's ridiculously overpowered in some respects, but storms are not something Kitten's good against.)