Slightly above normal temperatures are predicted across portions of the desert southwest, southern Rockies, west Texas and the southeast during the month of May. A surplus of total monthly cooling degree days of between 20 and 40 is projected across these regions.
Early-season energy costs with respect to cooling may be slightly higher than average as well. On the flip side, parts of the northern Rockies and northern Plains are forecast to see temperatures that on a whole average slightly below normal during the month of May. These areas of the country may see a few more extra late-season heating degree days than normal. Near normal temperatures are expected throughout much of the Great Lakes, Midwest, Mid-Atlantic, Northeast, and West Coast in May.
As for the weak La Nina in the Equatorial Pacific, it persisted because there has not been much change in the overall sea-surface temperatures during the past month. The latest long-range climate models are still indicating that this La Nina will weaken to a neutral phase over the next couple of months. When and how quickly this transition occurs could have an influence on temperatures during the upcoming summer season across the United States.