This summer the intense heat continued.
Cruel hot weather is the kind that's too much for anyone to handle. It's intense heat. Stranded in the desert in summer, heat.
This is a jukugo word that uses the on'yomi readings of the kanji. You didn't learn this reading for 暑 yet, so here's a mnemonic to help you:
Intense heat will show (しょ) on your face. You'll turn red and get all sweaty. You really can't hide it.