A whale was spotted in San Francisco Bay on Thursday afternoon near Pier 39, according to U.S. Coast Guard officials.

The whale was traveling east in the San Francisco Bay when it was seen around 3:30 p.m.

Coast Guard officials said a whale sighting in San Francisco Bay is fairly common in January.

Marin County-based Marine Mammal Center spokesman Jim Oswald said this time of year marks the gray whale migration. The whales are heading down to Baja.

For onlookers, Oswald advised using caution.

"It's wonderful to see them," he said. "Enjoy them from a distance."

A whale in the area becomes more of a concern when the animals head toward the San Joaquin Delta, where chances of getting stuck are higher, Coast Guard officials said.