During the past month, sea-surface temperatures across the equatorial Pacific have continued to show signs of warming. Much of the eastern Pacific is seeing warmer than average water temperatures while the central Pacific is seeing water temperatures only about 0.5 degrees cooler than normal. This indicates that the La Nina phase is continuing to weaken.
Latest climate models predict this La Nina phase will transition completely to a more neutral phase by late April or early May. As for May temperatures, climate data and a persistent positive North Atlantic Oscillation suggest that warmer than average temperatures are likely across portions of the Midwest, Ohio Valley, Tennessee Valley, Mid-Atlantic and Northeast. A surplus of early-season cooling degree-days by between 30 and 90 is expected throughout these regions.
Cooling costs could be higher than normal. Some climate indices suggest that parts of the southern Rockies and Desert Southwest will see warm conditions with higher than average cooling degree-day totals of between 30 and 60 during the month. The Pacific Northwest might see slightly cooler than average temperatures. Much of the rest of the western United States is projected to see closer to average May temperatures.