A cool, wet start to last year kept many motorcyclists off the road, making 2013 only the second year since 1997 that fatal bike crashes have declined, according to a report scheduled to be released Tuesday.

The report, by the Governors Highway Safety Association, projects a 7 percent decrease in the number of motorcyclists killed last year. The final fatality total is expected to be 4,610, down from 4,957 in 2012.

“It’s heartening that motorcyclist fatalities didn’t increase over the past couple of years, but they’re not decreasing either,” Kendell Poole, GHSA chairman, said in a statement. “Long-term gains in motorcyclist safety won’t occur because riders are deterred by bad weather, but from consistent use of proven countermeasures.”

The GHSA report comes in advance of federal data for 2013, which are expected to be released later in the year. The GHSA collects statistics directly from the state safety officers who make up its membership.

Comparing year-to-year numbers for the first nine months of 2012 with 2013, the GHSA said fatalities decreased in the District of Columbia and 35 states, increased in 13 states and remained the same in two.

In Maine, fatalities decreased from 21 in 2012 to 13 in 2013.

The National Highway Traffic Safety Administration said motorcycle deaths accounted for 15 percent of highway fatalities in 2011, though motorcycles amount to just 3 percent of vehicle registrations. NHTSA said injuries from motorcycle crashes increased to 93,000 in 2012 from 81,000 in 2011. Motorcyclists are more than 26 times as likely to die in a crash as occupants of cars, and five times as likely to be injured, NHTSA said.

Alcohol is a bigger factor in motorcycle crashes than it is for cars, with 27 percent of riders intoxicated, compared with 23 percent of drivers.

Motorcyclists killed at night are three times as likely than other drivers to have been drunk, NHTSA said.

Safety advances in cars and trucks have created a relatively steady decline in the overall national highway fatality rate, but many new features are not available on motorcycles.