- There is a slightly higher chance a La Nina will develop during the winter.
- Wetter and colder conditions are expected in parts of the North, and drier conditions in parts of the South.
A massive portion of the United States could be warmer than normal this winter if the La Nina climate phase kicks in, according to the National Oceanic and Atmospheric Administration.
There is about a 55 to 65 percent chance of a La Nina developing over the next several months, said NOAA's Climate Prediction Center in its winter outlook for 2017.
Only a small portion of the northern continental U.S. is expected to be colder than normal, mostly in a region from Minnesota to the Pacific Northwest, as shown in the map below.
La Nina is one of the phases of the El Nino Southern Oscillation, and it occurs when ocean temperatures in the southern Pacific Ocean drop slightly below their average.
NOAA said data favor wetter-than-average conditions across most of the northern U.S., from the Rocky Mountains to the Great Lakes. La Nina phases typically bring more snow in both the Rockies and around the Great Lakes.
Meanwhile forecasters expect drier conditions across the southern U.S.
It is expected to be both warmer and wetter than usual in Hawaii and northern and western parts of Alaska are expected to be warmer than normal as well.
Mostly everywhere else falls into the "equal chance" category for both precipitation and temperature. The climate signals in these areas are not strong enough to tilt the odds either way, NOAA said.