Originally the source material was in a yet unpublished novel form, written by John Katzenbach in 1982. The manuscript then landed on Producer David Foster's desk. Foster optioned it as a film, and the property then got published as a novel named "In The Heat of Summer".
The real-life Miami Police Department's S.W.A.T. Team appeared in the movie as the Miami Police Department's S.W.A.T. Team, in a scene where Kurt Russell's character enters the house of a victim. Many interiors were also filmed inside the Miami Police Department Headquarters.
The scorching trumpet solos performed during the Main Title music composed by the legendary Lalo Schifrin were done by Chuck Findley. Herb Alpert, another legendary jazz trumpet player, is featured in the score.
The blurb for the film's source novel "In The Heat of Summer" on source novelist John Katzenbach's personal website states: "They call July the 'Mean Season' in Miami, and this hot summer a clever, elusive killer is terrorizing the entire city. The death of the first victim was just a good story for reporter Malcolm Anderson, but the killer liked his style and begins to feed him a stream of front-page exclusives. His journalism makes Anderson a national celebrity - and they could make him the next victim . . .".
Director Phillip Borsos once said of this film: "I preferred to have it look somewhat stylized and slightly unreal, more what you would call a 1950's film-noir type of picture. I think making it slightly abstract, can be a way of reaching more people. When something is too real, that can almost be a way of limiting you".
According to website 'Wikipedia',"The Mean Season is named after the term of the same name, that refers to a pattern of weather that occurs in Florida during the late summer months. Hot mornings with sticky weather, lead into violent thunderstorms that blow in from the Caribbean and the Gulf of Mexico in the afternoon. However, the rain doesn't alleviate the heat, and only makes things hotter that evening. This cycle repeats every day for a month".
David Foster and Phillip Borsos observed how staff at the Miami Herald worked, and operated, for the production of the picture. Borsos once said of this: "I wanted to know what goes on at 3 p.m., at 5 p.m. There's a wonderful flow of traffic at different times of the day. Gradually, the room fills up. Later, there's a ferocious attack at the computer terminals. A lot of newspaper movies have ten people in the background, or fifty, but there's always the same level of action. If the script said 3:10 p.m., and the first edition was an hour off the streets, I wanted to know what would be happening".
The names of the water vessels which glide across the swamps are known as airboats or fanboats. The place where the boats sequences took place in the film featuring the vessels was the Florida Everglades in the Everglades National Park, Florida.