Overall, sea-surface temperatures across the Equatorial Pacific Ocean have continued to warm slightly during April. This indicates that the weakening trend for the current La Nina phase is persisting. Climate models continue to project that this La Nina phase will transition into a more neutral phase by June. As for the early summer temperature outlook, slightly warmer than average temperatures are expected across parts of the Great Basin and Desert Southwest with cooling degree-day totals higher by between 30 and 90 during June.
The ongoing drought conditions across much of Texas are expected to enhance warming throughout this region, which will result in above average temperatures and higher than normal early-season cooling costs. On the flip side, excess ground moisture across parts of the Northeast, Mid-Atlantic and Ohio Valley might help keep mean temperatures slightly cooler than average during June. Also, a possible negative North Atlantic Oscillation (NAO) during this time likely would lead to periods of cooler than normal conditions across the eastern third of the country.
Finally, there are some indications that the upper Midwest also could see a slightly cooler than average June with early-season cooling degree-day deficits of between 20 and 40 possible.