During the past of couple months, sea-surface temperatures across the equatorial Pacific have remained about 0.5 to 1.5 degrees warmer than average over most of the region. This indicates that the El Nino that developed early this summer is persisting. Most climate indices and long-range forecast models are now predicting that this El Nino will strengthen during the next few months and continue through at least the upcoming winter. As for the temperature outlook for September and October, slightly warmer than normal conditions are expected across portions of the Great Basin, Desert Southwest, Lower Mississippi Valley, and southern Texas.
Late season cooling degree-days are forecasted to see a surplus of between 60 and 180 across these portions of the country, which likely will lead to slightly higher than normal energy costs with respect to cooling. Some climate indices suggest that the Northeast also may see a slightly warmer than average fall as a result of the North Atlantic Oscillation (NAO) index predicted to be positive for most of the next couple of months. As a result, a deficit of early season heating degree-days of between 60 and 90 and lower early season energy costs with respect to heating are forecasted across this part of the country. Portions of the northern plains and upper Midwest might see mean temperatures average slightly cooler than normal, which will result in early season heating degree-days being higher than average by about 60 to 90. A more seasonable September and October is predicted for much of the Midwest, Great Lakes and Southeast.