Yep. Heat is a bigger factor in a race/run than hills. Case in point, I had a slower finishing time in the flat but hot Manila Milo 21k than in the cold but hilly Baguio Milo 21k (assuming that both races were actually 21 kilometers).
And it wasn’t just me, you could also see this in the winner’s times. Eduardo Buenavista’s finishing time in Baguio (1:06:36) easily beats Anthony Cheptoo’s time of 1:12:43 in the Manila 21k.