Economists say the United States Federal Reserve will stick to its interest rate hike forecasts at this week's June meeting but the window to get two hikes through by the end of this year is narrowing.

The central bank is not expected to raise rates at the meeting concluding in Washington on Wednesday (Thursday for Australian traders) because of heightened market volatility but its forecasts – known as the dots – will be closely scrutinised for revisions. A weak payrolls report for May has also tempered enthusiasm for the Fed to resume tightening, which it has not managed since December 2015.