Suzanne on 99.9F:
"It is about internal temperature. When I refer to temperature, I mean the way you feel when you're aroused in some way, whether it's through fear, anger or love. The title stands for a slight fever. Cos the normal temperature in the Fahrenheit system is 98.6°. So it means a little sick. Enough to hear things in a strange way and enough to see things in a peculiar way. A little bit off the normal."
[...]
"It describes the stance of the album, which is not normal, off the norm, not wildly feverish but off the norm enough to create tension, enough to give you a straight dizzy hallucinatory feeling but not so much that you feel that you're out of your mind in listening to it. It seemed slightly hotter than maybe some of my other albums. the other albums have a much cooler tone to the whole sound of them."
Interview with Fátima Castro Silva in "Urgent Whispers" (http://watermarks.vega.net/urgent_whispers/index.htm)

"This was the most difficult song of the album. That was the song I was sitting there looking in the thesaurus and the rhyming dictionary with. Looking up synonyms and antonyms for hot, cold, fever, romance, anything I could get my hands on.."
[...]
"It's a flirtatious song."
The Suzanne Vega - Leonard Cohen Interview, October 1992 (http://www.vega.net/cohnint1.htm)

Suzanne on medical themes:
"Some of those medical themes is my way of amusing myself and being what I call funny. It's a very obscure kind of humor. Some of it is because I think the language of medicine is fascinating and has its own poetry in it. And some of it I think is probably cause when I came off the road in 1987 I was, not seriously sick, I'm really healthy, but I was anemic and I had asthma and bronchitis and stuff you get from being run down. But I think the main reason I work with these terms is because I feel that language itself is beautiful, and especially medical language is a way of talking about the body in a way that's intimate without being corny. Although I think I've probably taken it about as far as I'm going to take it. But, I do get letters from doctors. They say that the information is very accurate and could they use the lyrics in their own texts."
The Suzanne Vega - Leonard Cohen Interview, October 1992 (http://www.vega.net/cohnint1.htm), transcribed by Eric Szczerbinski

"It's a flirting song, the idea of being with a man and there's something off the normal happening. Things could rise," she says in a measured, rather school-prefectish voice. Sort of a dirty joke, a tease, the idea a person is on the edge of burning. A little like Peggy Lee's Fever but more specific. A little of the beat, which is how I see myself. […] I was in London and someone asked what the weather had been like in New York; I said, oh, zero degrees, and then that rang in my mind and I thought, wow, that's an interesting phrase, I'd like to write a song called Zero Degrees Fahrenheit. But I thought it was too much like Less Than Zero which is Elvis Costello so I thought, well maybe 99.9..." Goodbye Bedsit Blues - You Magazine, The Mail on Sunday, September 6, 1992 http://www.suzannevega.com/about/1992/youmagazine.htm

"It's really a simple song. It's a song about flirting with someone. It's not a song really about illness although some people seem to think it is. It's really more about flirting with someone and feeling that things could be heading in a certain direction, you might say." Suzanne Discusses Tried and TrueSuzanne Discusses Each Song on Tried and True september, 1998 http://www.suzannevega.com/about/1998/triedandtrue.htm