May to September is the practical visiting season — the riverside and the Black Forest hinterland are at their best, the Alpengarten is in flower, and outdoor cafés are open. July and August can be hot in the Rhine plain (28–32°C).
December brings the Pforzheimer Weihnachtsmarkt on the Marktplatz, a smaller and quieter Christmas market than Stuttgart's or Esslingen's, but pleasant for an afternoon. 23 February sees the annual commemoration of the 1945 air raid — a sombre civic occasion with church services and a procession to the Wallberg memorial.
The Schmuckmuseum and the Gasometer are good for any weather and a sensible focus on a wet day.