In a research note, Ashworth said he was "worried about an even bigger drop" than the predictions because regional manufacturing surveys showed "sharp deterioration" in August.
Economist Ian Shepherdson of High Frequency Economics was also worried about trends in the sector. In a research note, Shepherdson said the report was "a very big and pleasant surprise," but he warned the index has further to fall and investors should "enjoy this while it lasts."
Stocks got a boost after the report's release, with the Dow index (INDU) surging 230 points.
China's manufacturing sector also picked up in August, according to a pair of reports released earlier Wednesday, calming fears about the pace of that country's growth.
TN faces a slow economic recoveryManufacturing growth slows in September
