Supplemental to Jean-Marie Prival's answer:
The February 2020 event was already discussed here in a question posted the same day this went public: What is the second thermometer in the image from the Esperanza Antarctic temperature record?
twitter.com wmo.int bloomberg.com nytimes.com theguardian.com
The tweet contained an image of a literal analogue thermometer which did show the 18.3°C... but curiously enough, also another thermometer showing merely 10.0°C.
The answer to that question is that this pair forms a wet-dry bulb system for measuring humidity.
