Lowrie, who said he was feeling better before Saturday's game, said he was starting to feel "real dizzy" when he and the Red Sox's training staff decided that "enough was enough."
The game-time temperature in Texas was 99 degrees, but the heat index was well over 100. The Dallas-Fort Worth area has had 14 straight 100-degree days through Saturday.
Lowrie said the dizziness was the worst symptom he felt.
"My body temperature was pretty high," Lowrie said. "That's probably the main one. I was starting to get dizzy and felt like I wasn't going to be able to help on the field when I wasn't really seeing straight."
Lowrie said he had no idea what his body temperature was, but he could tell when he took his uniform off he was extremely hot. He said Friday night's weather conditions were the hottest of his professional career. Lowrie said he could feel it in his last at-bat against Darren Oliver.
"I felt like I was in a sauna really," Lowrie said. "It was kind of heavy."
Lowrie, who spent most of the season on the DL with mononucleosis, said he'd have to wait and see how he felt Saturday before knowing his availability for Sunday's series finale in Texas. Sunday's high is forecast for 104 degrees with a heat index between 108 and 112 degrees. The Red Sox are facing a tough left-hander in Rangers starter C.J. Wilson.
"The hope will be maybe he can play tomorrow," Francona said. "C.J. Wilson's a nice guy to have some righties in there. We'll just see. I don't think it's going to be 70 and breezy tomorrow."