US Inflation Holds at 3.4% as Energy Shock Drives Sharpest Monthly Price Rise Since May

US consumer inflation remained unchanged at 3.4% in the year to August, matching economists’ expectations and July’s reading.

However, the latest figures contained a warning sign beneath the stable annual rate: prices increased 0.4% during the month, marking the fastest monthly rise since May and suggesting that the escalating energy shock is beginning to filter through the US economy.

The figures, released by the US Bureau of Labor Statistics on Friday afternoon, represent the final major inflation reading before the Federal Reserve’s upcoming policy meeting. They arrived as Americans were confronting record prices at the pump, adding to concerns about how higher energy costs could affect inflation in the months ahead.

Core inflation, which excludes volatile food and energy prices, provided a more encouraging signal. It eased to 2.4% in August from 2.5% in July. The annual headline figure, the core reading and the monthly increase all came in exactly as economists had anticipated, but the acceleration in monthly prices was the clearest source of concern.

The 0.4% monthly increase was four times July’s 0.1% rise and represented the strongest monthly pace in three months. The annual inflation rate remained at 3.4% partly because the comparison is being made against a relatively strong increase during the summer of 2025.

What the figures mean for the Fed

Financial markets had already been leaning toward a rate increase at the Federal Reserve’s 16 September meeting before the inflation report was published.

CME’s FedWatch tool had placed the probability of a quarter-point increase at 67.4%, significantly higher than the roughly 40% probability recorded before Chairman Warsh’s Jackson Hole speech in late August. After the inflation figures were released, the implied probability of a quarter-point increase jumped to 91.6%.

Warsh’s first keynote address as Fed chair proved to be a major turning point in expectations. In the speech, he argued that the US economy had become stronger rather than weaker, said that labour-market conditions were consistent with full employment and indicated that he "would be hard pressed to describe broad financial conditions as restrictive."

His assessment of inflation was equally direct. Warsh said, "we must be confident that underlying inflation is moving to our objective, clearly and at sufficient speed. Otherwise, we have work to do."

The August inflation data provide arguments for both sides of that assessment. Core inflation has declined for a second consecutive month and is now just 0.4 percentage points above the Federal Reserve’s 2% target. That suggests underlying price pressures are continuing to move in the desired direction.

At the same time, the acceleration in monthly headline inflation points toward renewed pressure, particularly as energy costs continue to surge.

Warsh has also declined to specify the precise circumstances that would prompt the central bank to change policy. He rejected the use of forward guidance, arguing that it "has overstayed its welcome".

The Federal Reserve has kept its benchmark interest rate between 3.50% and 3.75% since December. Three regional Fed presidents dissented in July, arguing in favour of an increase. It was the largest number of policymakers voting in the same direction against the prevailing decision since 2016.

Energy shock adds to inflation pressure

Much of the renewed inflationary pressure is being driven by energy, and there is little indication that the shock is about to disappear.

US crude futures moved above $100 a barrel this week as fighting between American and Iranian forces intensified around the Strait of Hormuz. Washington has struck five Iranian tankers following attempted missile attacks against a US Navy warship, adding further uncertainty to global energy supplies.

Diesel prices are among the areas where the impact has become most pronounced. The US national average exceeded $6 a gallon on Friday for the first time in nominal terms, according to the American Automobile Association.

The increase is placing particular pressure on businesses and industries that depend heavily on diesel. Truckers and farmers are now paying roughly 63% more for the fuel than they were a year ago.

California has been hit even harder, with the average diesel price approaching $8 a gallon. Gasoline prices have also climbed sharply, averaging $4.22 a gallon across the country, compared with $2.98 before the war began.

The disruption is not limited to the Middle East. Ukrainian attacks on Russian refineries have prompted Moscow to prohibit diesel exports, removing approximately 800,000 barrels a day from the market. Disruptions around the Strait of Hormuz have eliminated another estimated 1.2 million barrels a day.

Together, the two conflicts have forced refineries with approximately 5 million barrels a day of capacity to shut down. Around 8% of global diesel supply is currently affected by disruptions.

The consequences are already beginning to spread beyond fuel prices. Some retailers have introduced delivery surcharges as transportation costs rise, while the effect of higher energy prices on grocery costs typically takes time to work its way through the supply chain.

That lag means the inflation figures released on Friday may not yet capture the full impact of the current energy shock.

For the Federal Reserve, the result is an increasingly complicated picture. Core inflation continues to edge closer to the 2% target, but rapidly rising energy costs are creating a new source of pressure just as policymakers prepare to make their next interest-rate decision. 

By fLEXI tEAM