The ENSO phase remains neutral as sea-surface temperatures across the equatorial Pacific Ocean have been unchanged more than a month. Sea-surface temperatures remain warmer than average by between 0.5 and 1.0 degrees Celsius across the eastern Pacific, which indicates that an El Nino may still develop. The neutral phase will begin to transition to more of an El Nino during the next month or two. If an El Nino develops, it likely will influence the upcoming winter across parts of the country.
Warmer than average October temperatures are forecast across portions of the north-central Plains, upper Midwest and Great Lakes. Early season heating degree-day totals are expected to be at a deficit of between 30 and 90 during the month. There is also some indication that the North Atlantic Oscillation (NAO) might be positive during October, meaning slightly above normal temperatures for parts of the Northeast and Mid-Atlantic. Heating costs across these regions likely will be below average. Some climate indices indicate parts of California and the Great Basin might see slightly cooler than normal temperatures in October, which could result in a small surplus of heating degree-days. Much of the southern U.S. is forecast to see temperatures that will average closer to normal during October.