U.S. consumer prices likely rose at the fastest rate in nearly 40 years in May, data is expected to show Friday.

The Bureau of Labor Statistics' May Consumer Price Index (CPI) is expected to reflect a year-over-year increase of 8.3% last month, unchanged from April’s print, according to consensus estimates compiled by Bloomberg. On a monthly basis, economists forecast the broadest measure of inflation rose at an accelerated pace of 0.7%, compared to 0.3% in April.

Ahead of Friday’s report, experts predict a surge in gasoline prices will prove a driver of inflation for May after a recent rise back to all-time highs. In April, a moderation in the price of energy offered a temporary relief to inflation after Russia’s invasion of Ukraine rocked global commodities markets in March.

“Current year-ago rates are benefiting from base effects, but by mid-summer these will no longer be of help,” economists at Wells Fargo said in a note Wednesday. “In addition, gas prices soared in May, taking back the short-lived reprieve that they offered in April.”

Core CPI — which excludes the highly volatile food and energy sectors and is closely watched by policymakers — may be a bit of a bright spot in Friday’s report.

Economists expect core inflation rose 5.9% year-over-year and 0.5% month-on-month, per Bloomberg data. These figures would mark a slight cooldown from increases of 6.5% and 0.6%, respectively, in April.

Beyond serving as a gauge of the costs everyday Americans shell out for groceries, gas, housing and other goods and services, May’s consumer price index comes just before the Federal Reserve is poised to further ramp up interest rates at its policy-setting meeting next week.

Investors anticipate the Fed will raise its benchmark interest rate by 50 basis points, or 0.50%, on June 15; an increase of the same magnitude is expected in July. Persistent inflation readings may set the table for an increase of this magnitude in the fall as well.