The most prevalently quoted conventional 30yr fixed rates are at the lowest levels in a month as of today, but there are a few "yeah buts" that make that achievement look a bit less lofty.
The first is that the rates seen on any day this week would have qualified for the same distinction if they'd remained intact today. Reason being: there was a big rate spike last month on April 10. On a related note, today's rates weren't appreciably lower than those seen on Tuesday.
Still... lower is lower and we'll take it!
Today's improvement wasn't guaranteed. It required some sacrifices in the economic data with Jobless Claims coming in higher than expected. Then in the afternoon, the scheduled auction of 30yr US Treasury Bonds was met with solid demand. Both events helped put downward pressure on rates with many lenders ultimately issuing mid day reprices with better terms.
All of the above has played out in a very narrow range in the bigger picture. The big spike on April 10th was in a completely different league and it was exclusively a response to the Consumer Price Index (CPI). With that in mind, the next CPI will be released next Wednesday. It has just as much power to cause just as big of a move as it did last time, for better or worse.