Heat Wave (1998) was the fifth Heat Wave professional wrestling pay-per-view (PPV) event produced by Extreme Championship Wrestling (ECW). The event took place on August 2, 1998 from the Hara Arena in Dayton, Ohio. This was the first edition of Heat Wave to be broadcast on pay-per-view. The event also featured talent from Frontier Martial-Arts Wrestling (FMW) due to partnership between ECW and FMW.

Six professional wrestling matches were contested at the event. The main event was a Street Fight in which Tommy Dreamer, The Sandman and Spike Dudley defeated The Dudleys (Buh Buh Ray Dudley, D-Von Dudley and Big Dick Dudley). On the undercard, Taz successfully defended the FTW Heavyweight Championship against Bam Bam Bigelow in a Falls Count Anywhere match and Masato Tanaka defeated Mike Awesome. The event also featured FMW's Ace Hayabusa's first and only major wrestling appearance in the United States as he teamed with Jinsei Shinzaki to take on Rob Van Dam and Sabu for the World Tag Team Championship.