Will monthly inflation increase by 0.4% in September?

Analysis

Gasoline did the heavy lifting in August. Official records show the index for gasoline rose 3.9 percent that month, accounting for over a third of the overall increase that pushed seasonally adjusted CPI-U up 0.4 percent, following a 0.1 percent rise in July. That is a sharp jump, and sharp jumps driven by one volatile category rarely repeat themselves the very next month. The case for a lower September print rests on that math. Energy price spikes tend to be choppy rather than sustained, and without another gasoline surge of similar size, the arithmetic pushing the headline number to 0.4 percent again gets harder to replicate. July's 0.1 percent reading is a reminder that the underlying trend before August's spike was much softer. There is no consensus estimate for September specifically in the official record yet, and the data itself will not be published until October 14. That absence of a hard forecast number is exactly why the outcome carries real uncertainty rather than a settled answer. Anyone treating August's reading as a new baseline is getting ahead of the evidence. The single thing to watch is gasoline and broader energy prices through September. If pump prices spiked again on a seasonally adjusted basis, a repeat 0.4 percent print becomes far more plausible. Absent that, the case for a smaller move looks stronger, but only the October 14 release will settle it.