Just looked back at the mortgage interest rates from September 2023 and it's interesting to see how much things have shifted. Back then, the 30-year fixed was sitting at 8.04% with a 15-year at 7.19%. The jumbo rates were around 7.85%. These numbers show how volatile the market was during that period.

What caught my attention is understanding what actually drives these rates. It's not just random—the Federal Reserve's decisions and inflation data play huge roles. When the Fed raises its benchmark rate, it gets more expensive for banks to lend, which pushes mortgage rates up. On the flip side, when inflation cools and rates get cut, you typically see rates come down too.

If you were looking at a 100k mortgage back then at 8.04%, you'd be paying around 737 a month just in principal and interest, which adds up to about 165k in total interest over 30 years. Pretty substantial. The APR was different from the stated rate too—it was 7.99% when the rate was 8.04%, because APR includes lender fees on top of the base interest rate.

For anyone trying to actually qualify for better rates, the usual factors still matter: having a credit score above 670, keeping your debt-to-income ratio below 43%, and putting down at least 20% if you can. That last one helps you skip private mortgage insurance entirely. Different loan types also made a difference—conventional loans, FHA loans, VA loans, USDA loans, and jumbo loans all had different requirements and rates.

The whole mortgage interest rates landscape in September 2023 was basically a case study in how economic conditions ripple through the housing market. Rates were elevated compared to historical averages, and borrowers had to be strategic about their moves.