"Negative" vs "Minus" when referring to the temperature below zero?

I have read in some dictionaries that, when referring to the weather, the “–” sign is spoken as “minus” — for example “minus 10 degrees”.

Is “negative 10 degrees” also common and interchangeable with "minus"?

Not common, but yes, interchangeable.

To my ear, "negative X degrees" is normal, and "minus X degrees" is a bit affected. However, Janus Bahs Jacquet is of the opinion that "minus X degrees" is normal worldwide.

I'm inclined to trust him. I have very little experience with sub-0 Farenheit temperatures. Seattle has literally never gone below 0 F. I lived in Vancouver where it hit negative Celsius temperatures maybe once or twice, so I'm by no means an expert.

I'm leaving out Google Ngram below because the question specifically requests "spoken as," which Google Ngram doesn't index at all. The Corpus of Contemporary American English and British National Corpus do have entries (in theory) for transcribed spoken English.

Newspaper Usage

However, my hypothesis of regional variation isn't correct though. The Vancouver Sun and the Seattle Times both prefer "minus."

• "Temperatures hit chilly minus 3 degrees C at YVR this morning" (VS)
• "24 outdoors items to put on your holiday gift list" (ST)

Although both do infrequently use "negative X degrees," the Sun once in an AP wire about Iowa and one about Kam Chancellor's hands:

• "The Latest: Subzero temps set records; warmer weather ahead"
• "Seahawks safety Kam Chancellor's hands look like snake skin because of the cold in Minneapolis"

I'm forced to conclude "minus" is indeed the standard, and "negative" an acceptable variation.

Corpus of Contemporary American English

The CCAE has tokens from both written and spoken English. It has 140 hits for MINUS * DEGREES, from 2 to 459, in both numbers and words. On the other hand, it has only 13 hits for NEGATIVE * DEGREES. At some point, I'd like to map the hits to see if there are areal tendencies.

I can't link to the search directly, but here's a link to the COCA home page to look it up for yourself: http://corpus.byu.edu/coca/.

British National Corpus

Like the CCAE, the BNC has entries from ``a wide range of genres (e.g. spoken, fiction, magazines, newspapers, and academic).'' It has 15 hits for MINUS * DEGREES and none at all for NEGATIVE * DEGREES indicating "negative" is at least an Americanism.

Conclusion

"Minus" is indeed what most North Americans and all Brits say. That said, "negative" is not wrong, and unlike a word like "inflammable," you're unlikely to be misunderstood if you use. I don't see any reason to recommend against "negative," although if you're unsure, you could prefer "minus."

Maybe someone can weigh in whether it's correct in a technical context to say "negative" over "minus."

Thinking about a number line or scale, any number below zero can be referred to as "negative" OR "minus". So mathematically and conceptually either works.

But conventionally, in reference to temperatures, "negative" doesn't get used. I also speak Swedish, and in that language it's the same - "minus" is always used for weather and temperature, never "negative".