Brittney Griner's signature locs are no more ... and, according to her attorney, it's all 'cause Russian prison temperatures were causing brutal hair freezing.
Maria Blagovolina, who repped the WNBA star in her trial in Russia, told ESPN on Thursday the 32-year-old got the haircut two Sundays ago ... after her 'do kept freezing following prison showers.
Blagovolina said rather than deal with the issue for an entire Russian winter, Griner elected to chop it all off.
"It's very cold in there and every time she washed her hair she got cold and would get a chill," Blagovolina said. "She should have waited until New Year's Day."
Griner had donned long hair for YEARS ... rarely ever letting the flow get shorter than shoulder-length.
The basketball player looked ecstatic nonetheless while leaving Russia on Thursday -- smiling with the new haircut while telling at least one person on her plane that she was "happy."
U.S. official John Kirby said Friday after Griner touched down in San Antonio that she's in "very, very good spirits" and "appeared to be, obviously, in good health."
Griner is now expected to be checked out by medical personnel in Texas ... before returning home to Phoenix.