Miss Grotke teaches the class that the fact that it is the hottest day of the year reminds us that we are as much affected by Global Warming as the rest of the Earth. When the fan breaks down, she tries to teach the class the power of visualization, however, this fails. Whilst most of the students think about places that are even hotter; only Gus manages to find a cold place to visualize, which he tries, but fails to tell the gang about throughout the episode. However, this could be because Spinelli kept on interrupting him. The gang tries to find various ways to cool off, but they fail.
Butch suddenly shows up and tells them about a backup water valve located right on the other side of the playground (which is seen as much bigger and being circled by crows). The gang decides to find it; unfortunately, the heat is so unbearable, that in Gretchen's words, "Every inch could seem like a mile." The gang eventually runs into King Bob, who deems their search a royal quest. They eventually try to stop at the Ashleys' Clubhouse, however, the snobbish Ashleys seem to be enjoying the heat, and they refuse to let in the gang. Lawson shows up and challenges Vince to see who can get the hottest before he begins to pass. The gang argues, but Gus then tells them to be quiet, as he can't concentrate.
He then goes on to tell his story: he and his father chase after a criminal who is about to do catastrophic damage to the stock market. This takes place in the coldest day in the Alps; they are accompanied by a dog named Hoodlum. They eventually catch up and detain the criminal, who ends up covered in snow. After the story is finished, the gang finds out that they are at the valve, and they learn the power of visualization. Gus is given the honor of turning the valve, and so turns on sprinklers all over the playground, re-hydrating the school. As the episode ends, various students of Third Street School are seen running around and playing the water from the sprinklers.
- Animation error: When the gang is walking under the sun for the second time, Gretchen's underlip is missing while she is shown holding a handkerchief.
- Animation error: When T.J. says "To conserve our energy" after the gang (excluding Gus) started to walk, Spinelli's nostrils appear for a few frames.
- Naming error: On Disney+, the title is known as "The Coolest Heatwave Ever".
- Spinelli, T.J., and Butch have their jackets around their waists throughout most of the episode. T.J. and Spinelli were only seen with their jackets on in the classroom.
- This episode was loosely based on the comic story, "The Long Hot Recess".
- Starting with this episode, the end of the credits dropped the "All rights reserved" from "(c)[Year] Disney Enterprises, Inc". The Paul & Joe Productions vanity card logo also started to appear after the credits.
- This was the first episode to use generic, split-screen credits. The regular credits sequences for Season 5 would not be shown until 2003, when Disney Channel and Toon Disney began showing the series.
- On Disney+, this episode is paired up with "Mundy, Mundy" and vice versa.
- This is the third and final time the Ashleys (Excluding Ashley T.) are seen in their bathing suits; the first two times being "Yes, Mikey, Santa Does Shave" and "The Ratings Game".
- This is also the third time Ashley T. is shown wearing her bathing suit; the only episode she continues to wear her bathing suit is in "League of Randalls".
- This is the second and final time Butch is shown not wearing his jacket; the first time being in "The Experiment" in a flashback.
- Mikey putting his potato bag over his head is a reference to Lawrence of Arabia.
- Gus' story of how he, his father, and his dog caught the criminal is a parody of various Johnny Quest episodes.
- This episode was cut from the Italian dub.
- This episode was paired up with "Mundy, Mundy" outside the US.
- This episode is "Lost" from the Latin American dub.
- T.J. Detweiler - Andrew Lawrence
- Vince LaSalle - Rickey D'Shon Collins
- Ashley Spinelli - Pamela Segall-Adlon
- Gretchen Grundler - Ashley Johnson
- Mikey Blumberg - Jason Davis
- Gus Griswald - Courtland Mead
- Miss Finster - April Winchell
- Miss Grotke - Allyce Beasley
- Randall Weems - Ryan O'Donohue
- King Bob - Toran Caudell
- Butch - Kath Soucie
- Ashley Armbruster - Anndi McAfee
- Ashley Quinlan - Rachel Crane
- Erwin Lawson - Erik Von Detten
- Gus' Dad/DeSilvo - Sam McMurray
- Gordy - Sam Gifaldi
- Phil - Justin Jon Ross
- Judy - E.G. Daily
- Hoodlum - Frank Welker