Portions of the Great Lakes, Midwest, and possibly parts of the Northeast are forecast to see temperatures that average slightly below normal during the month of March. If the NAO (North Atlantic Oscillation) index can become negative over the next month, more of the Northeast and Mid-Atlantic region could see periods of colder than average temperatures in March as well.
A surplus of total monthly late-season heating degree days of between 30 and 60 is projected throughout these regions of the United States. Late-season energy costs with respect to heating will also likely be somewhat higher than average. In contrast, slightly above average temperatures are predicted across parts of west Texas, the southern Rockies, and Desert Southwest during the month of March. A heating degree day total deficit of between 20 and 40 is forecast throughout these parts of the United States. Much of the Southeast, Plains, Rockies, and West Coast are expected to see temperatures that on a whole average closer to normal in March.
As for the weak La Nina phase, it is still persisting for now. The latest long-range climate models continue to indicate weakening of this La Nina during the upcoming spring season. Time will tell how this will affect the temperatures across the United States this summer.