The most accurate foreign-exchange forecasters say the dollar's best quarterly rally since 2008 has no chance of continuing to year-end as a slow economy spurs the Federal Reserve to flood the world with more U.S. currency.

Led by JPMorgan Chase & Co., the five best strategists as measured by Bloomberg News in the six quarters through September see the currency averaging $1.34 per euro in the final three months of 2011, from $1.3387 on Sept. 30. They estimate it will average 76.6 yen, from 77.06.

Reports on everything from jobs to housing and incomes show the world's largest economy may be in jeopardy of slipping back into recession, forcing the Fed to print more money for the third time in three years to inject into the financial system through bond purchases. Forecasters say the strategy would debase the dollar, which is down 22 percent since March 2009 even with last quarter's gains.