Despite a temperature of 19 degrees at kickoff, Adams threw five touchdown passes to lead Eastern Washington (11-2) into the playoff quarterfinals.
Quincy Forte rushed for 202 yards on 21 carries and a touchdown.
"It was really easy," said Forte, who scored on a 20-yard run during the second half in which the Eagles outscored the Jackrabbits 27-3. "I was just picking through holes. The (offensive) line did a super job."
Adams targeted seven different receivers, four of which caught touchdowns. He was 12-for-22 for 217 yards.
Cooper Kupp caught two touchdown catches, giving him an FCS record of 20 this season. He had four catches for 90 yards, giving him 81 catches, which ties an FCS freshman record.
Kupp has a TD catch in 13 straight games.
"Personal accolades just come with this team," Kupp said. "Throughout the year, our third quarters have been good. We came out and did it again today."
The game was tied 14-14 at half, but the Eagles dominated the second half on both sides of the ball and outscored the Jackrabbits 27-3 in the last two quarters.
The Jackrabbits put together an eight-play, 75-yard drive that ended with Reggie Gandy's 14-yard TD pass from Austin Sumner on their first drive. It was the only lead of the days for SDSU (9-5).
SDSU finished with just 88 yards rushing. That included 71 by FCS leading rusher Zach Zenner, who finished the season with 2,015 yards.
Eastern Washington answered SDSU's score with 2:12 left in the first quarter when Adams found Gehring from 22 yards out on a simple post patter. Kevin Miller tied it at 7-7.
Less than three minutes later, Adams threw 40 yards to Kupp for a 14-7 lead. It stayed that way until Zenner took a direct snap and dived in from the 1 to tie the game at 14-14 with 1:40 left in the half.
Forte was a workhorse in the second half.
"We just worry about winning," Forte said. "Whether I get two rushing yards or 200 receiving, I just want a W for our team."
SDSU quarterback Austin Sumner was 26-for-40 for 315 yards.
EWU won the national title in 2010 and are appearing in the playoffs for the seventh time in 10 years. It finished the regular season ranked No. 3.