During the past month, the La Nina phase has transitioned to a neutral El Nino Southern Oscillation (ENSO) phase. Sea-surface temperatures continue to be slightly warmer than average across the eastern Pacific but near average throughout much of the central equatorial Pacific.
The latest climate models indicate the ENSO phase will remain neutral through at least summer. Several climate indices suggest warmer than average July temperatures across the Desert Southwest and throughout parts of the central and southern Rockies and Intermountain West. Parts of the Desert Southwest could be much warmer than average with a surplus of cooling degree-days of between 60 and 120 for the month. Cooling costs likely will be higher than normal across these regions. Ongoing drought conditions could aid in a warmer July across parts of the southern Midwest, Tennessee Valley and Southeast with total cooling degree values higher than average by between 30 and 90 projected.
The North Atlantic Oscillation (NAO) could be negative during parts of June and July. If this occurs, extended heat waves would be less likely across the Midwest, GreatLakes, Northeast and Mid-Atlantic. Mid-summer temperatures closer to normal are anticipated throughout these regions.