noun, noun which may take the genitive case particle 'no'
high temperature and humidity; hot and humid
Describes a climate or environment that is both hot and humid, often used in weather forecasts, product storage conditions, or health advice.
日本の夏は高温多湿で過ごしにくい。
Japanese summers are hot and humid, making them uncomfortable.
この薬は高温多湿を避けて保管してください。
Please store this medicine away from high temperature and humidity.
蒸し暑い is an adjective meaning 'muggy' or 'sultry', focusing on the oppressive feeling of humidity, while 高温多湿 is a more technical or formal noun/adjectival phrase stating the condition of high heat and humidity.
Compound of 高温 (high temperature) and 多湿 (high humidity).