BOSTON -- On the hottest day of the year in Boston, David Ortiz led the Red Sox to their biggest offensive attack of the season.

Ortiz continued his torrid hitting with a grand slam for one of their four homers as they set a season high in runs, beating the Miami Marlins 15-5 on Wednesday night.

The Red Sox pounded out 16 hits and won their fourth straight game and sixth in their last seven on a night when the game-time temperature was 95 degrees.

"The weather warmed up a little. Guys felt loose," Boston manager Bobby Valentine said.

Ortiz hit his 18th homer of the season, his third in three games and fourth in six, a span in which he is 9 for 20. The grand slam in a six-run fourth inning was the 11th of his career.

"I don't get many opportunities (with pitches) over the plate," he said. "I just try to be patient for that one pitch they give me to hit."

The Red Sox moved out of last place in the AL East at 35-33, passing Toronto after the Blue Jays lost 8-3 to Milwaukee.

Mike Aviles, Jarrod Saltalamacchia and Will Middlebrooks also homered one night after Ortiz hit one of Boston's three homers in a 7-5 victory over Miami.

"Hitting is definitely contagious and so is winning," Aviles said. "Any time you get a couple of wins together you just get that good confidence going and you just keep rolling with it and that's where we're at right now."

The Marlins lost for the 12th time in 14 games despite getting four runs and nine hits in six innings against Felix Doubront (8-3).

Ricky Nolasco (6-6) gave up nine runs and nine hits in 3 1/3 innings.

"I just think we're all trying to get on a positive run right now," he said. "It's just not happening. The last two games we swung the bats well. We just haven't pitched (well)."

The Red Sox offense has come alive in the past week with at least seven runs in four of their last six games.