moderately heated sake
Refers to sake warmed to a moderate temperature, typically around 45–50°C, warmer than ぬる燗 (lukewarm) but cooler than 熱燗 (hot).
Let's have a drink with moderately heated sake today.
Compound of 上 (じょう, 'upper' or 'moderate') and 燗 (かん, 'warming sake'). The term refers to a specific temperature range for warmed sake.