There has not been much change to sea-surface temperatures throughout much of the Equatorial Pacific Ocean during the past month. Sea-surface temperatures in the eastern Pacific continue to run slightly cooler than average. This indicates that while the ENSO phase currently remains neutral, there is still a possibility of a weak La Nina developing during the upcoming fall and winter months. Right now, most long-range climate models suggest about a 55-60 percent chance of this La Nina developing over the next couple of months.
As for the September outlook, slightly above normal temperatures are forecast across the Great Lakes, Ohio Valley, Tennessee Valley, Mid-Atlantic, and Northeast. Portions of the Desert Southwest, Intermountain West, and south-central Rockies are also projected to see temperatures that average slightly warmer than normal during the month of September. These regions of the country are expected to see a late season surplus of total monthly cooling degrees of between 20 and 60 as well as slightly higher than average energy costs with respect to cooling. Temperatures are forecast to average closer to normal across much of the Gulf Coast, West Coast, northern Plains, and northern Rockies during the month of September.