The number of Americans seeking unemployment benefits jumped to a seasonally adjusted 382,000 last week, the highest level in two months.
The Labor Department says applications increased by 15,000 in part because of the impact of Hurricane Isaac, which disrupted work in nine states and boosted applications by 9,000.
The four-week average, a less volatile measure, increased for the fourth straight week to 375,000.
Applications for unemployment benefits reflect the pace of layoffs. When applications fall consistently below 375,000, it usually indicates that hiring is strong enough to lower the unemployment rate.
The figures come after a disappointing jobs report last week. Employers added only 96,000 jobs in August, below July's gain of 141,000 and far below the average 226,000 a month added in the January-March quarter.