Hi Karen:
The most likely "culprit" is the weather (i.e., drought). My guess is that lack of "growing season" precipitation in your area had a significant impact on the fruiting and cone production (i.e., less than normal) of trees in your general area.
Yes, other more "localized" factors could come into play...(spring frosts, excessive spring rains, etc.), but I wouldn't know those details specific to your geographic area.
Best of luck!