Question
What is the cause of ponderosa pines to not have any pine cones.  does this have something to do with the weather?
Thanks for you input.  We have about 25 Ponderosa pines and there are no cones this year.  We live in Paradise, California which is in the Sierra Nevada foothills.  

Answer
Cone production will vary greatly in ponderosa pine from a heavy crop to none. No regular periodicity has been observed in the seed production of ponderosa pine over its entire range. In California, west of the Sierra Nevada, medium seed crops are borne on an average of every 2 to 3 years. The average interval between heavy cone crops is 8 years. Good cone crops are produced every 3 years in the Black Hills , every 3 to 4 years in the Southwest , and every 4 to 5 years in the Pacific Northwest .