The 27-month run of year-over-year growth in cargo passing through the gates of the Port of Savannah came to a halt in February.

The Georgia Ports Authority said this week that container volume in Savannah declined last month by 8.5 percent compared to February 2018. But it wasn’t due to tariffs, trade wars or shaky economic conditions overseas.

The culprit, rather, was fog.

Foggy conditions on the Savannah River shut down the channel to ships for about 160 hours last month, or about a quarter of the available time for freighters to transit the busy shipping lane, GPA Executive Director Griff Lynch said.

Consumer goods, produce, industrial parts, autos, timber and other products flow in and out of Georgia’s Savannah and Brunswick ports. But the lack of visibility forced ships to wait for clear passage.

The Brunswick port also was affected by fog, with automotive cargo volume down about 5 percent compared to the same month a year ago.

Despite the February downturn, the ports said container traffic is up 8.8 percent to 2.97 million 20-foot equivalent units, or TEUs, so far in the fiscal year that started in July 2018.

Automotive cargo through Brunswick also is running ahead of the prior fiscal year.

“It really was just an anomaly,” Lynch said. “We typically have some fog events in the winter months, but this was much worse.”

March is likely to be strong as shippers made up for the February delays, he said.

Georgia's inland and coastal ports are vital cogs in the state's economy, and, in some ways, canaries in the global economic coal mine. The volume of cargo that flows in and out of the Savannah and Brunswick harbors are bellwethers of U.S. demand for imports and of the appetite abroad for Georgia grown or manufactured products.

The ports set a record for the 2018 calendar year, and its Savannah harbor moved 4.35 million TEUs. That amounted to a 7.5 percent increase from a year earlier.

Trade tensions between the U.S. and China and instability elsewhere have been a headwind for the global economy.

The 2018 growth was buttressed in part by shippers trying to get as much product to shore as possible to avoid costly tariffs. Lynch said the ports saw some increased activity at the end of the year and in January because of tariff fears.

Global trade remains strong, though demand from China could soften in the coming months. Still, Lynch said fiscal year 2019, which ends in June, will likely set new records.