As franco_nigro mentioned, it can be horribly humid in Jul-Aug at least in downtown Salerno;I've found that the air is actually a little drier and cooler on the Costiera Amalfitana, Penisola Sorrentina, and the Costiera Cilentana than in downtown Salerno. Many locals in downtown Salerno(and north of and including Napoli) flee to the Costiera Cilentana as the area is a great August destination not to mention less expensive than the Costiera Amalfitana, Capri, and/or Sorrento.
To note, the drive down to where the pool is in Salerno from Castellabate or Santa Maria di Castellabate is pretty long. Parking near the pool can be nutty and must be sought across the street along one of the side streets. However, in general, to get to the pool (known to many locals in Salerno as pisciana comunale), one could consider making the trip Mon-Sat/non-holidays using the #34 CSTP bus from Santa Maria di Castellabate(1 hour 40 minute ride) to Salerno. Then one could get off in the Torrione District (tell #34 CSTP driver, La Carnale or "piscina comunale (pee SHE nuh come moo NAWL eh)") and walk to the pool which is around 2+ streets toward the ocean (bus stop at your back, one way traffic going left to right, go straight out) and to the following structure. In general, across the street from the pool is a tall hill with an ancient fort ("La Carnale") on top and next to a newer looking church:
http://www.salernofoto.it/ALBUMSALERNO37/pisc_vitale.jpg
Otherwise, one could take a #34 CSTP bus all the way to the Salerno FS Train Station and then catch an infrequent #41 or #46 CSTP bus from the Salerno FS Train Station to the closest CSTP bus stop to the pool(tell driver, "Piscina Comunale" to be let off at the closest CSTP bus stop):
http://www.cstp.it/orarioasp/suburbunico.asp?numero=41&direzione=andata
http://www.cstp.it/orarioasp/suburbunico.asp?numero=46&direzione=andata
The walk from the CSTP bus stop where the #34 Salerno-bound CSTP bus lets you off(2-3 bus stops before the Salerno FS Train Station) to the Piscina Comunale isn't too bad/ugly although the walk from the stop right before the Salerno FS Train Station is nicer as one could use the new concrete walkway next to the new Grand Hotel to reach the street which runs along the ocean (could tell #34 CSTP driver, "Grand Hotel"). When going back, one needs to find the closest CSTP bus stop on the street in front of the pool entrance. The CSTP bus stop must list the green/blue #34 bus line on the bus stop, otherwise, the #34 CSTP won't stop at that particular CSTP bus stop. Also, when the blue #34 CSTP bus stop approaches, one needs to stick one's arm out to signal the driver to stop.
Buona Fortuna...