And of course the interest rate on a conventional first mortgage will be somewhat different than the rate on an FHA loan, and different than it would be on a car loan, and different that it will be for someone with a credit score of less than 760, different for an investor, different for a 2nd home, different for a home equity loan, different for a line of credit, different for a 2nd mortgage, etc.
The prime rate depends on who your bank is, the Federal Funds rate is unpredicatable, and the LIBOR is anyone's guess!
Does that answer your question?
Your loan officer will have the latest guess as provided by her lender, and that is probably as good a source for info as any. If anyone knew for sure what the interest rate would be in the future, he or she could make huge amounts of money by playing the market.
(Humor was intended here, in case you thought I was being serious)
I took the liberty of providing a link to a mortgage calculator that I share with borrowers.