The game resumed with a runner on first and two outs for the Rockies in the bottom of the sixth.
"Once the game started it was business as usual," Rockies manager Walt Weiss said.
Neither team threatened until the eighth when Pence delivered to help the Giants win a season-high seventh straight game. With Christian Friedrich (0-1) on the mound, Andrew Susac opened the inning with a single to left. Gregor Blanco moved him over with a bunt, then Friedrich struck out Angel Pagan for the second out of the frame. Adam Ottavino came on in relief and served up a run-scoring double to Pence.
Buster Posey followed with an infield single before pinch-hitter Travis Ishikawa blooped an RBI single to right. Posey was hung up in between second and third on the play, but the damage was done.
Brandon Barnes singled with two outs in the home half and Sergio Romo averted trouble when Charlie Blackmon just got under a 1-1 offering, lifting it to the base of the wall in center for a flyout to end the inning.
Santiago Casilla allowed a leadoff single to Ben Paulsen in the ninth, but induced a 6-4-3 double play from Josh Rutledge. Justin Morneau kept the Rockies going with a single before Nolan Arenado grounded out weakly to shortstop to end the game.
Jeremy Affeldt (1-1) picked up the win for tossing 1 1/3 scoreless innings as play resumed.
Two rain delays lasting more than an hour each forced the suspension of the contest on May 22, the last time San Francisco visited Denver.
Colorado's Wilin Rosario singled to lead off the second and advanced to third on back-to-back groundouts. Following a walk, Michael Cuddyer hit an infield single to the right of shortstop Brandon Crawford, whose throw didn't reach first, giving the Rockies an early 1-0 lead.
After the first rain delay, which lasted an hour and 22 minutes, the Giants' bats came alive in the fourth.
Pence smacked an 0-2 slider from Tommy Kahnle over the right-field fence to tie the game at 1-1. Michael Morse later drew a two-out walk and came around to score on a Pablo Sandoval double to center.
David Huff, who took over for Giants starter Tim Hudson after the stoppage, escaped a bases-loaded jam in the fourth after Morneau popped out to catcher Buster Posey in foul territory to end the threat.
Arenado and Corey Dickerson both singled to right to put runners on the corners to start Colorado's half of the fifth. Rosario then grounded into a double play to tie the game at 2-2.
Casilla was placed on the 15-day disabled list due to a right hamstring strain back in May ... Rockies starter Jorge De La Rosa pitched three scoreless innings with just one walk before the first delay ... Hudson allowed one run on five hits and two walks in three innings ... Pence entered with a 13-game hitting streak, but his double in the eighth does not count toward it because the game counts for May 22.