With temperatures unseasonably high in the 80s, the Pirates improved to 5-1 on their homestand.
"They are just hitting everything," Brewers manager Ned Yost said after his team lost its fourth consecutive game. "They hit good pitches, they hit pitches we get up a little bit. ... They are just red hot right now."
The Pirates have scored 56 runs in their last six games -- 9.33 per contest -- and have outscored the Brewers 32-5 in taking the first three games of a four-game series that concludes Thursday.
Players throughout the Pirates lineup are swinging the bats well. Freddy Sanchez had three hits and scored three runs, Sean Casey homered and improved to 6-for-12 with five RBI since coming off the disabled list Monday, Jack Wilson extended his hitting streak to 11 games and Bay hit his team-record-tying 12th home run of the month.
"Hitting is contagious," Casey said. "A lot of guys are hitting right now. It all started with Jason Bay the last few weeks, and I think everyone's just feeding off of that."
But it's Castillo who is leading the way. He sent a 2-2 pitch from Chris Capuano (5-4) just over the right-center field wall with Sanchez aboard in the second inning.
Castillo, who entered with an NL-leading .419 batting average since May 9, has eight homers this season after entering the year with only 19 in 753 career at-bats.
"Castillo is swinging such a good bat right now that it's fun hitting behind him," said Sanchez, who joined Castillo in having streaks of seven hits in seven at-bats snapped in the seventh inning. "You get to score a lot of runs."
It is the second home run streak by a Pittsburgh player in the past week. Bay had his six-game run snapped Monday against the Brewers.
"It's a lot easier to hit when the guys around you are hitting, and it's not do-or-die every time you step to the plate," Bay said. "There can't be too many teams with a guy in the seven hole with the kinds of numbers [Castillo] has."
Sanchez -- dropped to the sixth spot in the order when Casey was activated -- singled twice and doubled in his first three at-bats, and Castillo followed his home run with a single before walking and reaching on an error. The last Pirates player with seven hits in seven at-bats was Wilson from May 31-June 2 last season.
"I feel like I could have been just a little sharper," Capuano said. "But basically I just think we ran into a truck this series."
No. 8 hitter Ronny Paulino gave Pittsburgh a 3-0 lead in the fourth inning when he singled home Sanchez. Even Pirates starter Ian Snell collected his first major-league hit and RBI when his fifth-inning single drove in Sanchez.
"We've had the guys perform in the middle of the order," Pittsburgh manager Jim Tracy said. "But what's been happening is our six, seven and eight guys did significant offensive damage. That great to see."
Casey and Bay hit back-to-back home runs to lead off the fifth. It was the 17th home run for Bay and Casey's third. The Pirates have homered in 13 of 14 games (28 total).
Pittsburgh's offensive performance overshadowed its strong starting pitching for the second consecutive night. Snell worked six innings and allowed one run -- Jeff Cirillo's second home run that led off the sixth -- three hits and two walks, striking out two.
"I finally let my team make plays," said Snell, who has won four of five starts. "It feels good to let my defense make plays and have the offense hit like they did."
Bay set the Pirates' record for home runs in May with 12, the most in any month by a Pittsburgh player since Brian Giles had 12 in August 1999. ... The Pirates, who beat the Brewers 14-3 on Monday and 12-1 on Tuesday, have not scored at least 10 runs in three consecutive games since Aug. 27-28, 1930. ... Sanchez is hitting .374 (89-for-238) since Sept. 16, tops in the majors over that span. ... There have been 67 home runs hit at PNC Park in 27 games -- 39 by the Pirates, who have 19 in their last eight home games. ... The Brewers were held to three hits.