SPRINGFIELD — MGM Springfield reported gross gambling revenue of just $18.9 million for December — the lowest full-month revenue figure in the casino’s 16-month history.

The disappointing December 2019 numbers follow gross gambling revenue of just $19.9 million in November, which at the time was the second-lowest monthly total since the casino’s first full month of operation in September 2018.

MGM Springfield reported gross gaming revenue of $21.6 million a year ago in December 2018.

The new numbers come amid fears that MGM Springfield is losing out in an over saturated gaming market and to neighboring New York and New Hampshire that have legalized sports betting.

Before opening in August 2018, MGM Resorts International told regulators the casino would bring in an average of $34.8 million a month. Instead, the average over the first 16 full months was $21.54 million a month, with a high of $26.9 million in September 2018, its first full month of operations.

The Massachusetts Gaming Commission released its monthly figures Wednesday.

Encore Boston Harbor reported gross gaming revenues of $54 million in December, an improvement from $47 million in November and $45 million in October.

Gross gambling revenue at the slots-only Plainridge Park Casino was $10.2 million in December, down a bit from $10.9 million in November. Year-over year, Plainridge was also down from $14 million in December 2018.

Michael Mathis, president of MGM Springfield, blamed December’s numbers on inclement weather despite Encore Boston Harbor being up for the month.

“We’re grateful for the many guests who braved some of December’s most inclement winter weather days in order to be with us, and thrilled many of them were winners at the slots and tables," Mathis said in a prepared statement. "We’re looking forward to Red Sox’s Winter Weekend in a few days welcoming thousands of passionate baseball and Red Sox fans to downtown Springfield. We’ll be ready to greet them and showcase the best in entertainment and hospitality in New England.”

MGM Springfield also generated $4.7 million in taxes on that gaming activity, according to the Massachusetts Gaming Commission. That also is the lowest total in the casino’s history.

To date, the Commonwealth has collected approximately $525 million in total taxes and assessments from Plainridge, MGM and Encore since the respective openings of each facility.

MGM Springfield’s parent company, Las Vegas-based MGM Resorts International, has indicated it’s working on a deal to sell the casino real estate to an investment company and then lease the facility back while maintaining control of the business.

The real estate transaction would be part of a national “asset light” strategy for MGM.

Springfield Mayor Domenic Sarno wasn't worried Wednesday after hearing the numbers.

"Mother Nature can create ebbs and flows for any business," Sarno said. "It was a difficult December."

He noted that the gambling revenue doesn't include money MGM is less likely to make public, like hotel room revenue and money earned in restaurants and in in retail.

Also, Sarno said a dip in gambling revenue doesn’t impact city finances.

Under a 40-year tax agreement through the state’s Chapter 121A program, MGM Springfield pays the city a set amount annually, beginning at $17.6 million.

The tax payments increase in future years, and average about $23.3 million a year.

"That's why I negotiated a tough deal, the city is guaranteed its money," Sarno said.

He said the solution to falling gambling revenue is the path MGM is taking: hosting more special events.

“I know that MGM and Mike Mathis are retooling in bringing n new and different types of aspects that will enhance what MGM has on offer here,” Sarno said. I know we are all looking forward to a big Red Sox weekend."

Sarno said he’s supportive of sports betting but recognizes that it won’t be a big revenue stream. instead, it will make MGM Springfield competitive as a destination.