If he had been wrong, the first nuclear blasts would have happened minutes later.
"Twenty-three minutes later I realised that nothing had happened. If there had been a real strike, then I would already know about it. It was such a relief," he recalled.
A later investigation concluded that Soviet satellites had mistakenly identified sunlight reflecting on clouds as the engines of intercontinental ballistic missiles.
Petrov, who retired with the rank of lieutenant colonel, died on 19 May but news of his passing became widely known only this month, thanks to a chance phone call.
German film-maker Karl Schumacher, who first brought Petrov's story to an international audience, telephoned him to wish him a happy birthday on 7 September only to be informed by his son, Dmitry Petrov, that he had passed away.
Mr Schumacher announced the death online and it was eventually picked up by media outlets.