By Tony Bizjak, Sacramento Bee

Motorcycle deaths rose nationally in 2012, a study found, and the culprits may have been warmer weather and economic changes.

Notably, though, California motorcycle fatality numbers were slightly down.

The Governors Highway Safety Association is estimating motorcycle deaths topped 5,000 across the country last year, a 9 percent increase from the previous year, in part because better weather lengthened the motorcycling seasons in many states, and also because higher gas prices prompted more people to drive motorcycles.

“With the economy improving in 2012 and further strengthening in 2013, more people have disposable income for purchasing and riding motorcycles,” the report concludes. “At the same time, high gas prices may cause more individuals to choose fuel-efficient vehicles like motorcycles as their preferred mode of transportation.”

California was among the handful of states were motorcycle fatalities dropped from the previous year. During the first nine months of 2012, the months for which data were available, the number of motorcycle deaths in California dropped slightly from 321 to 318.

Officials credited increased awareness campaigns in California as part of the reason. Highway officials last year launched an aggressive “share the road” campaign aimed at making car drivers more aware of motorcyclists.

The report notes that only 19 states have helmet laws that apply to all riders, down from 26 in 1997.