Yes, black suits are hot in the summertime. But the much more important issue is making sure that, as a new-guy amateur racer, you pick a color that doesn't make you look like a dork or - worse yet - like some Top Gun school reject poised to run amok on the track.
A black Sparco two-layer suit is is a perfect choice for a new guy. Oral surgeons driving Porsches have a monopoly on silver suits. For God's sake save the red ones for the Ferrari guys.
One-layer suits are dangerous and some associations require Nomex undies (which look great, cost a fortune, and are comfortable only in the Klondike) with 2-layer suits.