Translation guide
In Japanese, Celsius is expressed as 摂氏 (せっし) or more commonly just 度 (ど) after the number. The word セルシウス (セルシウス) is also understood but less common.
Referring to the Celsius temperature scale in general or as a unit.
Formal term for Celsius, often used in written or technical contexts. Can be combined with 度 (ど) as 摂氏度 (せっしど), but 摂氏 alone is sufficient.
水は摂氏100度で沸騰する。
Water boils at 100 degrees Celsius.
The most common way to say 'degrees Celsius' in everyday conversation. Simply attach 度 to the number. Context usually makes it clear it's Celsius.
今日の気温は25度です。
Today's temperature is 25 degrees (Celsius).
Katakana rendering of 'Celsius'. Recognized but less natural than 度 or 摂氏. May be used in some product names or when emphasizing the scale.
この温度計はセルシウスとファーレンハイトの両方に対応しています。
This thermometer supports both Celsius and Fahrenheit.
In daily conversation, Japanese people almost always use 度 (ど) after the number to express temperature in Celsius. There is no need to explicitly say 'Celsius' unless contrasting with Fahrenheit.
明日は30度を超えるらしい。
It seems it will exceed 30 degrees tomorrow.