Australia had an unusually early and fairly severe flu season this year. Since that may foretell a serious outbreak on its way in the United States, public health experts now are urging Americans to get their flu shots as soon as possible.

“It’s too early to tell for sure, because sometimes Australia is predictive and sometimes it’s not,” said Dr. Daniel B. Jernigan, director of the influenza division of the Centers for Disease Control and Prevention. “But the best move is to get the vaccine right now.”

The number of cases of flu in this country is still quite low, according to the weekly C.D.C. FluView released Friday . But as the weather cools, it is expected to ramp up.

In 2017, Australia suffered its worst outbreak in the 20 years since modern surveillance techniques were adopted. The 2017-2018 flu season in the United States, which followed six months later as winter came to the Northern Hemisphere, was one of the worst in modern American memory, with an estimated 79,000 dead.