Commodity prices have been rising, and this has raised some concern about rising inflation across the board. Speaking last week in Los Angeles, John C. Williams , CEO of the Federal Reserve Bank of San Francisco , gave his prognosis on inflation. In short, he expects inflation to peak in the coming months, and then "return to an annual level of about 1¼ to 1½%." Williams: There are several reasons for thinking the inflation bulge will be short-lived. First, commodity prices are not likely to keep increasing indefinitely at a rapid rate. Indeed, in recent weeks, prices for a number of commodities, including sugar and cotton, have fallen sharply. In addition, the prices of contracts for certain key commodities in the futures markets, such as crude oil, indicate that traders believe these prices won’t keep rising at double-digit rates. For example, the numerous supply disruptions that have pushed up prices of some foodstuffs, such as poor harvests in Russia and China, are not likely to be repeated. So even if commodity prices remain elevated, they won’t keep pushing up inflation. A second reason for believing that inflation will peak and then trend down is that higher commodity prices generally represent only a small proportion of the cost of the finished goods American consumers buy. For example, corn and sugar make up only a fraction of the cost of a box of Frosted Flakes. Most of the cost comes from the labor involved in manufacturing, distributing, and selling the breakfast cereal, including paying for air time for Tony the Tiger. This means that large percentage increases in commodity prices typically translate into relatively small percentage increases in consumer prices. Of course, some goods, such as gasoline, have very high commodity input shares. But, in today’s economy, these are more the exception than the rule. The stability of longer-term inflation expectations is a third factor that leads me to expect that inflation will start to ease later this year. It’s true that surveys show that consumers expect moderately high inflation over the next year. Households see gasoline prices going up and up and up, and, not surprisingly, they get worried about near-term inflation prospects. But medium-term measures of inflation expectations have barely budged. In other words, ordinary Americans agree that we are seeing a transitory rise in inflation. Those survey results reflect the fact that inflation has remained low and relatively steady for several decades and that the public believes the Fed is committed to keeping inflation under control. As long as household, business, and investor inflation expectations remain stable, then it’s unlikely that an inflationary dynamic will become established or that underlying inflation will jump sharply. Read the full speech here .