What’s ahead this winter: Snow boots or sandals?

Whether you’ll experience a dry, mild winter or a wet, cold one will be all about the seesaw dance of warmer and cooler seawater in the tropical Pacific Ocean that produces the climate effects known as El Niño and La Niña, government forecasters said Thursday.

This year, a dry, mild winter is likely across most of the southern USA because of a developing La Niña, but the northern tier of the nation could get walloped by a colder and wetter winter, the forecasters said.

Another forecast, released this week by the private firm Atmospheric and Environmental Research, said colder- thannormal temperatures are expected for much of the East and warmer than normal temperatures are likely in the West.

Forecasters at NOAA’s Climate Prediction Center issued their official U. S. winter outlook Thursday, saying La Niña is expected to influence winter weather across the USA this year. La Niña is the cool counterpart to El Niño, which dominated the winter of 2015- 16.

This forecast predicts only where above or below normal temperatures — and above or below normal precipitation — are most likely. It does not predict how much snow will fall or the severity or length of cold snaps.

The Atmospheric and Environmental Research forecast looks at a variety of factors, including how much snow is on the ground in Siberia in October and the extent of Arctic sea ice in September.

The La Niña climate pattern — marked by cooler- than- average water in the central Pacific Ocean — is one of the main drivers of weather around the world. The prediction center issued a “La Niña watch” last week.