It's still only the beginning of July, but it's already being over 35℃ and I'm feeling tired from the summer heat. I guess I'll just have to wait for the summer to finish.
この場合、次のような言い方ができますよ。
ーIt's still only the beginning of July, but it's already been over 35℃ and I'm feeling tired from the summer heat. I guess I'll just have to wait for the summer to finish.
「まだ7月初旬なのに、すでに35℃を超えていて夏バテしています。夏が終わるのを待つしかないのかな」
It's still only the beginning of July「まだ7月上旬である」
to feel tired from the summer heat「夏バテを感じる」
I'll just have to wait for the summer to finish「夏が終わるのを待つしかない」
または次のようにも言えます。
ーThere's nothing I can do except wait for the summer to be over.
「夏が終わるのを待つほかない」
ご参考まで！
カナダ 
