… sorry, in #4, “you will meet many of the requirements for a BS in chemistry (gen ed, for example, and some of the sciences) with your MS in meteorology” – that should be in your BS in meteorology.
And only the specific graduate department can advise you what kinds of chemistry, etc., classes you’d need after your BS in meteorology, and how long it would take to complete them, before you’re eligible to apply for a Master’s. It will vary from school to school.
I will add, you will save yourself a lot of time, money and hassle by just majoring in chemistry as an undergraduate.