Last year there were many areas on the east coast that saw a dramatic drop in acorn production. This excerpt is from the Washington Post as to possible reasons why:
"Being a nut-bearing tree, an oak's life cycle is directly tied to seasons, and its productivity is dependent on weather. For example, white oak tree flowers are pollinated in the spring; acorns grow and mature throughout the summer; and acorns fall to the ground in autumn. According to the U.S. Forest Service, anthers (the flower parts that produce pollen) on white oak flowers open and close with changes in humidity. Also, a very rainy spring can damage flowers, delay pollen production or reduce pollen dispersal. The most productive white oak acorn seasons are those with a stretch of 10 warm days followed by a few weeks of cool days; whereas, the least productive are those in which cool temperatures precede warm.
The weather could be one factor in the lack of acorn crop this year. As you may recall, spring of 2008 was wet, with a May rainfall total of 10.66 inches -- the second wettest on record. The rainy spring was preceded by several months of drought.
Even though a single mature white oak can produce 10,000 acorns annually, it will also go through years of little to no acorn production depending on external conditions. One year without acorns shouldn't cause us too much worry. However, it is definitely something to monitor; if the lack of acorn crop becomes a trend, this behavior could be an indication of other environmental and climatic factors at play."
White oaks are apparently cyclical in their acorn production - a bumper year is often followed by a year of lower production. Other oaks I understand are more consistant.