We have seen this movie before. As the American summer progresses, growth prospects are steadily downgraded and pressure builds on the US Federal Reserve to ease monetary policy further. By September, the doves win out and the Fed embarks on aggressive easing. That is what happened in 2010 and 2011. The only question is whether the Fed will move pre-emptively at its open market committee meeting this week or choose again to wait until autumn.

The arguments are finely poised. The case for waiting has merit. Ben Bernanke faces the familiar law of diminishing returns. Having already pledged to maintain zero interest rates until 2014, there is little left to be squeezed from that lemon. Extending the zero-bound pledge to 2015, say, would have only marginal credibility. Mr Bernanke’s term expires the previous year. In addition, the Greek election outcome raises hopes of a pause in that other movie: the trial and tribulations of the euro.

But the merits to the Fed acting now are probably stronger. Many forecasters project US growth will drop below 2 per cent for the year – well below the level at which US unemployment would continue to fall. Some fear the US jobless rate may even rise in the coming months. At its last meeting in April, the Fed projected 2.7 per cent growth in US gross domestic product this year. After three months of flat or falling retail sales and manufacturing, the Fed will almost certainly revise its forecasts downwards. US inflation also looks to be heading below the Fed’s 2 per cent target.