Pitești has a continental climate — hot summers and cold winters, with the Carpathians providing some shelter from the harshest northern winds. Spring (April–May) and autumn (September–October) are the most comfortable for a visit. Summer is fine for the city itself but essential for the Transfăgărășan road, which only opens in July and closes by October with the first serious snowfall.
If you're visiting for the surrounding county rather than the city, time your trip for the wildflower season in the mountains (late May to July) or the autumn foliage (September to mid-October). The Curtea de Argeș Monastery hosts a pilgrimage in September around the Feast of the Assumption that draws large crowds.