I know Ororo is "immune" to temperature variations. But the way she said it in this issue, I interpreted as a post traumatic effort. Like when you use a muscle beyond what you are used to, that you feel weaker, feel pain... or in this case cold. It's not the kind of thing that was set in stone for me.
And even if she just felt cold because of the rain. These characters are so old, have so much history, I personally think it is understandable if somethings change over the years between writers or if they don't know everything. It's not like this is something that changes who Storm is or her function in the story.
I think it is very disrespectful that people call this shitty writing because of a little detail, even though the writers created a cool concept and are using all the characters for something. It really feels like a team book, and we only had 2 issues total (with so many characters). Issue 3 has Storm and Erik discussing in the cover, so we can expect some focus on them there. If she is bad used there (or before), I sure will complain about her characterization, but we don't need to be unfair.