Seasonally adjusted exports jumped 2.4 percent month-on-month and imports inched up just 0.3 percent, data from the Federal Statistics Office showed.
The consensus forecasts in a Reuters poll of economists were for exports to slide 0.5 percent and imports to gain 0.3 percent.
The seasonally-adjusted trade surplus widened to 18.3 billion euros from a revised 16.3 billion euros in July.
The consensus forecast was for it to narrow to 15.3 billion euros.