We've had some beautiful cool weather here in Atlanta this spring. It's about 50°F outdoors as I write this, one week into the month of May. The high yesterday was only about 70°F.
We're getting a few more heating degree days (HDDThe difference between the 24-hour average (daily) temperature and the base temperature for one year for each day that the average is below the base temperature. For heating degree days, the base is usually 65 degrees Fahrenheit. For example, if the average temperature for December 1, 2001 was 30 degrees Fahrenheit, then the number of heating degrees for that day was 35.) in the middle of May. (Heating degree days are really just another way at looking at temperature, which I explained in more detail in a look at the fundamentals of degree days.) We occasionally pick up some HDD even in July and August. But it's the winter HDD that matter for heating — and that give us a clue about the climate.
from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/heating-degree-days-drop-again-2017