This is a popular statement in American English now.
For fun, I searched Google separately for “has a temperature” and “have a temperature” (each with the quotation marks, to avoid variations) and got about 589,000 matches and about 427,000 matches, respectively.
But to say that someone “has a temperature” means nothing except for the negative connotation beneath its euphemistic form.
Someone usually says or writes “He has a temperature.” to tell the listener or reader, respectively, that the subject of the sentence has a higher-than-normal temperature.
But the noun “temperature” by itself has no positive or negative value.
Can you imagine someone, such as a non-native-English speaker, first reading or hearing “He has a temperature.” or “You have a temperature.”?
The statement would be meaningless to such a person.
The noun “temperature” must be modified by an adjective to give it value.
Otherwise, you are speaking in euphemisms.