Over the past month, sea-surface temperatures across the eastern Equatorial Pacific Ocean have began to cool slightly. While time will tell for sure, this could be the first small sign that the present El Nino is beginning to weaken.
Long-range climate models continue to indicate that the El Nino will weaken to a neutral phase by late spring or early summer and that a La Nina may begin to develop during the fall. One thing to watch for is if this strong El Nino does indeed weaken over the next few months, it could lead to a hotter than normal summer across parts of the eastern half of the United States, particularly across the Midwest and Plains. It is too early to tell, but this is a trend that will be monitored in the months to come.
As for the temperature outlook for the month of April, slightly above normal temperatures are forecast across portions of the Pacific Northwest, northern Rockies, Midwest, Great Lakes, Mid-Atlantic, and Northeast. Late-season heating degree day totals are projected to be lower by between 20 and 60 during April across these regions of the country.
In contrast, parts of the southern Rockies and Four Corners region are expected to see temperatures that on a whole average slightly below normal, which will lead to a little higher than average number of total heating degree days for April. Much of the north-central Plains and Southeast will see temperatures that average closer to normal.