Can you please advise me on writing temperatures? Do we use ºC or the words degree Celsius?
Style Manual answer
Temperatures didn’t make it onto the Measurements and units page for the live release. It’s possible they could be added at a later stage.
The answer is in the SI units brochure, which is linked on the page. You’ll find it on page 149, at paragraph 5.4.3.
The symbol comprises 2 elements: the base degree symbol (°) and ‘C’ for ‘Celsius’. This symbol is common enough that there’s no need to spell it out. So it’s the first of the 2 renderings you’ve given.
The other rules in Style Manual all apply, such as using a non-breaking space between the value and the symbol.
For example, you would have ’28 °C’, and ‘minus 4 °C’ or ‘−4 °C’. (For negative temperatures, you would need to use the minus symbol if you decided to set your style without spelling out the word.)