When I see the word inferno, I think fire, but originally, the word did not carry the connotation of intense heat. The association with burning derives from beliefs taught by some religions about the afterlife.
The OED offers only one definition of inferno:
Hell; a place of torment or misery compared to hell; a place likened in some respect to the Inferno of Dante’s Divine Comedy.
Merriam-Webster offers three definitions of inferno:
1. a place or a state of torment and suffering.
2. a place that resembles or suggests hell in being dark, noisy, chaotic, lawless.
3. intense heat.
English speakers, British as well as American, use inferno to mean an intense conflagration:
Tracking the inferno: where wildfires are hitting California, other states hardest—The Guardian.
Scientists find planets that survived red giant inferno—The London Times.
Thirty people feared dead and 40 more injured after shopping centre inferno causes mall to collapse in Russia —The Daily Mail.
Multiple fire departments reported to the scene of the inferno just after 7 p.m. Sunday, and spent nearly the next 12 hours battling the blaze.—Galloway Patch (New Jersey).
Small Fire Becomes Inferno, Burning Homes in California—New York Times.
Like inferno, the adjective that derives from it, infernal, refers to the realm of the dead or a place of punishment after death:
Paradise Lost opens with the fallen angels in hell. Mammon proposes that they build an infernal kingdom of their own, imitating the majesty of heaven through the material riches of the kingdom of hell.
Infernal is commonly used as a synonym for hellish, damnable, damned, diabolical, and fiendish. Here are some examples:
City Tells Ice Cream Trucks To Keep That Infernal Racket Down
When will these so-called “voters” stop with their infernal meddling?
Will you stop with your infernal fear-mongering?
Gatlin and his ilk have brought not only themselves down with their infernal lies but the whole athletics community.
I turned my eye towards him and immediately caught his eye, which he kept staring upon me for more than a minute, with the most infernal expression I have ever seen upon a human face.
An “infernal machine” is “a machine or apparatus maliciously designed to explode and destroy life or property, especially one in the form of something harmless. For example:
To greet the Prince’s return to Sofia this month, the Chief of the Russian Secret Police sent him an infernal machine disguised as a box of the finest cigars.— Sherlock Holmes and The Case of The Bulgarian Codex, Tim Symonds, 2012.