Sea-surface temperatures across much of the Equatorial Pacific Ocean continue to run slightly warmer than average. During December, there has been little change, and no real further warming has occurred. Most climate models still indicate a 55 to 60 percent chance of at least a weak El Nino developing during the next month or two. If a weak El Nino develops, it probably will have more minor effects on temperature and precipitation trends across the U.S. during the winter. It will be monitored nevertheless.
As for January, slightly warmer than normal conditions are expected across parts of the Pacific Northwest, northern Rockies, Great Basin and northern California. A deficit of monthly heating degree-days of between 30 and 60 is anticipated, which likely will result in slightly lower than average heating costs in these regions.
Meanwhile, slightly cooler than normal temperatures are predicted throughout portions of the Northeast, Mid-Atlantic, Southeast and Tennessee Valley. The NAO (North Atlantic Oscillation) could become negative again by January, and, if so, this tends to lead to surges of colder air coming out of Canada across the eastern third of the country. Parts of the northern Plains and upper Midwest also might see below-normal January temperatures. A surplus of heating degree-days along with slightly higher heating costs are predicted across these regions.