What do you think?
Can we use It’s raining  to talk about the future?
Can we use It’s raining instead of It will rain?
Always? Sometimes? What’s the difference?

Part of the answer is  how you feel about grammar.
Is English grammar prescriptive or descriptive?
My ear says It’s raining can be ok for the future tense.
Your grammar book, and your brain should be
saying it is incorrect.
What do you think?