Marijuana sales in Colorado topped $1 billion in 2015, according to a new report from cannabis investment firm the ArcView Group.

Estimates put the figure at $1.005 billion, up nearly 45 percent from about $700 million last year. Growth was primarily driven by recreational sales, which topped $600 million. Medicinal sales in the state came in just above $400 million.

Industry insiders had long predicted revenue would cross the $1 billion mark, though a sluggish end to the year was unanticipated.

“(The fourth quarter) did not continue the momentum of (the third quarter),” said Roy Bingham, founder and CEO of BDS Analytics, and industry data analysis firm in Boulder. “In fact, Q4 came in well below Q3, suggesting among other things that this is a more seasonal market than might have been expected.”

Data from ArcView, based in San Francisco, showed that in Colorado and Washington, the two states in which recreational marijuana is legal, sales growth peaked in the summer months, with decided dips in the fall and early winter.

Nancy Whiteman, co-founder of Boulder’s Wana Brands, said that sales ebb and flow along with tourism in the state.

“Things really start to pick up in January and stay strong throughout ski season,” Whiteman said. “They go down a bit in mud season and up again in summer, which is the peak time.”

Still, despite a disappointing end to 2015, overall industry growth was a robust 30 percent, according to the report.

Nationwide, sales of marijuana for adult use (non-medicinal) were up a stunning 184 percent — from $351 million to $998 million last year.

“Many in the business and financial sector have taken a ‘wait and see’ approach to the legal cannabis industry,” ArcView CEO Troy Dayton wrote in the report. “The data in this report confirms (that) legalization of cannabis is one of the greatest business opportunities of our time and it’s still early enough to see huge growth.”

Still, the report cautioned, the industry is not without risk.

Last year, for instance, publicly traded marijuana stocks consistently underperformed the NASDAQ and S&P 500 indices, according to ArcView.

Shay Castle: 303-473-1626, castles@dailycamera.com or twitter.com/shayshinecastle