Motorcycle deaths are driving a dramatic increase this year in the number of overall traffic fatalities in Minnesota.

So far this year, 37 people have been killed while riding their motorcycles, more than double the number by this time last year.

June 19: MN motorcyclist deaths up 56 percent

But this year some motorcyclists may be hitting the road without the proper skills, said Donna Berger, the state's director of traffic safety. She noted that people who have not ridden motorcycles for a while often buy a new one when the economy improves.

"Perhaps they're hitting the years where they're now empty nesters, they're not spending all their money on their children, and they go out and get themselves a toy," Berger said. "It may be a bigger bike than they're used to riding, and they haven't honed their skills. They haven't been on for a number of years."

Good weather also may have had a hand in the spike in motorcycle deaths. A milder spring started the riding season earlier this year, which could have caused more people to hop on their bikes, Berger said.

Overall, 198 people have lost their lives in fatal traffic crashes so far this year, a 21-percent increase over the same period in 2014.

Last year, 361 people died on Minnesota roads, the lowest number of fatalities since 1944. Authorities attribute last year's decline to safer cars, improved road design, and other factors.

Officials said the Department of Public Safety is still analyzing this year's data to determine exactly what is fueling the trend. In many of the motorcycle crashes, no other vehicle was present and the riders were having trouble handling curves.

Correction (July 17, 2015): An earlier version of this story misattributed quotes about motorcycle deaths. Donna Berger, Minnesota's director of traffic safety, talked about the issue. The story has been updated.