Sea-surface temperatures across the equatorial Pacific have continued to average between 0.5 to 1.5 degrees warmer than normal over most of region during the past couple of months. This indicates that the El Nino, which has been in place since late summer, is holding in strength.
Most climate models predict that this El Nino will persist at least through the upcoming winter with some strengthening possible. As we look toward the winter temperature outlook, this current El Nino phase is expected to be one of the primary influences on temperatures across the United States.
Past years with similar El Nino events–specifically 1986 and 2006–indicate that slightly warmer than average temperatures are likely across portions of the northern-central plains, northern-central Rockies and Great Basin during late fall into early winter.
Total heating degree-days are expected to be lower by between 60 and 180 during November-December, which will lead to early-season energy costs with respect to heating being somewhat less than average across these regions of the country. Meanwhile, parts of the southern United States are forecasted to see slightly higher than normal early-season heating degree-day totals during November-December. This will likely be a result of the wetter, cooler conditions that typically develop across this part of the country during an El Nino winter.
Some climate indices also suggest that the Northeast will see cooler than average mean temperatures persist at least into November. As a result, a heating degree-day surplus of between 60 and 180 is expected over the next couple of months.