McLouth’s line drive to right on a 3-2 pitch off Doug Brocail (4-4) scored Jose Bautista and pinch runner Luis Rivas. Adam LaRoche, who went 3-for-4, hit his 10th home run earlier that inning, starting the rally with two outs.
The rain delays totaled 3 hours and 7 minutes - once in the top of the fourth for 2 hours and 39 minutes and again less than an hour later during the bottom of the sixth, when play was halted for 28 minutes.
Hunter Pence and Carlos Lee hit home runs to account for the offense for Houston. Lance Berkman walked four times and Brad Ausmus reached base four times for the Astros.
John Grabow (5-2) pitched two scoreless innings to earn the victory and Damaso Marte pitched the ninth for his third save.
Lee, who extended his hitting streak to 11 games, homered for the second time in two games with a rocket shot to the deepest part of the park in left-center field with Berkman aboard in the fifth. It was his 21st of the season.
Pence’s solo shot, his 11th, came with one out in the fourth, with a heavy wind heading straight out of the park and a storm just about to hit. The area was under a severe thunderstorm watch.
The following two batters reached against Pirates starter Ian Snell, ending his night after 3 2/3 innings. While T.J. Beam was warming up, umpire crew chief Wally Bell called the grounds crew in for the first time.
Snell was activated from the disabled list earlier in the day and was charged with one run on four hits and three walks with one strikeout. He had been suffering from medial epicondylitis in his right elbow.
Rain began to fall again shortly after play was resumed for the first time, picking up in intensity in the sixth. McLouth hit a solo homer, his 17th and second in two games, in the fifth.
