Nearly two dozen container ships are sitting anchored off the Southern California coast Friday as suppliers on land wait for goods to fill their delayed orders.

The problem has been going on for several months now and doesn’t appear likely to improve until summer.

Currently, about 20 ships sit anchored off the ports of Los Angeles and Long Beach, according to the Marine Exchange of Southern California, a service that monitors port traffic and operations. Another six ships are scheduled to arrive later Friday and join the waiting game.

At times there have been as many as 40 ships waiting; normally, there’s no more than a handful, according to the Marine Exchange.

Officials have blamed shortages of equipment and labor needed to unload the ships.

It can take 8,000 trucks to haul the cargo away from a ship, Marine Exchange executive director Kip Louttit said in March. When all those trucks hit the road, there aren’t enough available when dockworkers are trying to unload the next ships in port.

Lately, it has been taking five to seven days to unload a ship instead of two to three, said Shruti Gupta, an industrial analyst with the consulting firm RSM.