West Coast ports posted record cargo volume last month, opening the peak August-November shipping season on a strong note, officials at both ports said this week.

The Port of Los Angeles set a new single-month record in August, moving 861,081 twenty-foot-equivalent units (TEUs), the busiest August in the port's history and a 4.2% increase over the same period a year ago. Overall volume for the year is up 5.7% through August, officials said.

The port said imports increased 4.1% to 437,613 TEUs compared to August 2018, while exports fell 10% to 146,284 TEUs, the 10th straight monthly decline of exports. Empty containers increased 13.8% to 277,183 TEUs, officials said.

The Port of Oakland opened peak season with cargo volume growth as well, handling 88,323 TEUs, a 3.1% increase over the year-ago period and the port's busiest August on record for inbound loads, officials in Oakland reported. Exports rose 1% and empty container shipments fell 14%, officials said.

Oakland officials attributed the August increase to strong U.S. consumer demand as well as overseas demand for American farm goods, which resulted in higher exports. Oakland's exports have risen year-over-year for six straight months, officials said.

"It's good to see volume trending in the right direction," Port of Oakland Maritime Director John Driscoll said in a statement. "Let's see now if we can keep it going through the fall."

Officials in Los Angeles said they don't expect to keep pace with the "extraordinary influx" of imports the port saw in the final months of 2018, when retailers raced to beat anticipated tariffs on Chinese goods.

"We don't expect to see those kind of volumes in the months ahead," said Port of Los Angeles Executive Director Gene Seroka, pointing to uncertainty surrounding the ongoing U.S.-China trade war. "We need a negotiated settlement of the U.S.-China trade war to restore global trade stability."

August-through-November is shipping's highwater mark, officials said, the time of year when U.S. retailers import holiday merchandise. Cargo volumes can be a harbinger of the shipping industry's health as well as a broader economic indicator.