From what I've heard, we haven't had this many hot days in a row for several decades.
ーFrom what I've heard, we haven't had this many hot days in a row for several decades.
「聞いたところによると、こんなに暑さが続くのは数十年ぶりらしい」
from what I've heard, ... で「聞いたところによると…らしいよ」
we haven't had this many hot days in a row for several decades. で「こんなに暑い日が続くのは数十年ぶりだ」
ご参考まで！
It seems like it's been decades since we've had a heatwave this long.
「こんなに暑さが続くのは数十年ぶりみたい」という表現を英語で伝えるために、次のようなフレーズを使えます：
It seems like it's been decades since we've had a heatwave this long.
"decades" は「数十年」を意味し、"heatwave this long" で「これほど長く続く暑さ」というニュアンスが伝わります。
カナダ 
アメリカ合衆国 
