noun
hot summer; sweltering summer
Refers to a summer characterized by intense heat; often used in literary or emphatic contexts.
今年の炎夏は記録的な暑さだった。
This year's hot summer brought record-breaking heat.
noun
midsummer; middle of summer
Specifically indicates the peak or middle period of summer, often with a nuance of intense heat.
炎夏の候、皆様にはますますご健勝のこととお喜び申し上げます。
In this midsummer season, I hope you are all in good health.