Re: we'll be in for it
For example, if your mother told you that you had to be very careful to keep your clothes in good shape because you had to wear them to a party that nigh, then getting your clothes soaked by the rain would get you in trouble with your mother. In that case, you'd be "in for it" if you didn't have a raincoat or an umbrella, but it's because your mother would upset with you.
Otherwise, getting soaking wet might be uncomfortable, but it doesn't get you in trouble, so "in for it" doesn't work.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.