Run, don't walk, to lock in your mortgage rate today. Today's borrowers could score one of the lowest rates that we've seen all month.

The average interest rate on a 30-year, fixed-rate mortgage dropped to 7.1% APR, according to rates provided to NerdWallet by Zillow. This is 10 basis points lower than yesterday and 18 basis points lower than a week ago. (See our chart below for more specifics.) A basis point is one one-hundredth of a percentage point.

The Federal Reserve will announce its rate decision later today, when central bankers are expected to hold the federal funds rate steady. We're especially interested in the post-meeting press conference, where investors — and lenders — will be hanging onto Fed chair Kevin Warsh's every word as an indicator of future policy moves. Markets are currently projecting that a rate hike will be coming in December.

The Fed doesn't directly set mortgage rates, but mortgage rates do move with the federal funds rate.…