States with the warmest May before 1900

Georgia 76.2 1896
Idaho 58.2 1897
Indiana 68.4 1896
Kentucky 71.5 1896
Michigan 62.4 1896
Mississippi 77 1896
North Carolina 72.3 1896
Oklahoma 75 1896
South Carolina 76.5 1896
West Virginia 67.3  1896  

States with the warmest May from 1900 to 1999

Alabama 76.1 1933
Arkansas 74.1 1962
Colorado 59.5 1934
Connecticut 63.1 1991
Florida 78.6 1905
Illinois 69.5 1962
Iowa 68.8 1934
Kansas 71.2 1962
Louisiana 77.3 1933
Maine 57.6 1911
Massachusetts 61.4 1944
Minnesota 64 1977
Missouri 72.1 1962
Montana 59.6 1934
Nebraska 68.5 1934
New Hampshire 59.7 1911
New Jersey 66.1 1991
New Mexico 66.8 1996
New York 61.6 1911
North Dakota 63.1 1977
Ohio 67.5 1991
Oregon 58.6 1992
Pennsylvania 64.8 1944
South Dakota 68.3 1934
Tennessee 72.7 1962
Texas 78.4 1996
Utah 61.8 1934
Vermont 59.9 1975
Virginia 68.8 1953
Washington 60 1958
Wisconsin 63 1977
Wyoming 57.5 1934

States with the warmest May this century

Arizona 72.1 2000
California 69.6 2001
Delaware 69.2 2004
Maryland 69 2004
Nevada 62.1 2001
Rhode Island 61.8 2010