I answered a similar question about the Allied bombing campaign vs the Blitz here. This may give you some insight as to what the Allied bombing campaign was like for Germans.

If you can find the excerpt you're talking about, I'd be happy to type up an answer that addresses your question directly.

"Firestorm" has a spectrum of meanings. With the broadest meanings, it is used to refer to almost any large and destructive conflagration. With a narrow meaning, it is restricted to fires that produce a large surface-level radial inflow of air at high speeds (e.g., 100-200km/hr or more), which feeds a large rising convective columns which reaches an altitude of many kilometres.

Using this narrow definition, there are three confirmed urban firestorms known, all from bombing during WWII: Hamburg, Dresden, and Hiroshima (and three additional possible firestorms: Kassel and Darmstadt in Germany, and Ube in Japan). The are multiple accounts by witnesses of all three confirmed firestorms of the hurricane-force winds, and some accounts of people being sucked in. Mathematical/computational modelling of firestorms confirms that such high winds are to be expected, when the right conditions are met (which is not often, which is why there were relatively few firestorms in WWII despite repeated efforts to produce them).

Accounts of the winds are generally not exaggerated. Multiple witnesses described them, and they are theoretically expected. In addition to the urban cases, firestorms have resulted from large forest fires, also with very high wind speeds.

The POW you mention is probably Victor Gregg, author of Dresden: A Survivor's Story, February 1945 (Bloomsbury, 2013). He describes the winds in his book, and has also described them in interviews. Gregg was captured during the Battle of Arnhem, and was one of the few people whose life was saved by the bombing of Dresden - he was sentenced to death at the time, due to be executed the day after the bombing. He escaped during the bombing and took part in the firefighting and rescue effort, witnessing the raid and the firestorm.

The most famous witness in the English-speaking world was Kurt Vonnegut, who spent the raid in Dresden, but sheltered in an underground meat locker - he witnessed the aftermath, but not the raid itself. His experiences were the basis of his novel Slaughterhouse-Five. Vonnegut isn't your witness, since he didn't see the raid and the winds, just the destruction and death that resulted.