Mountain heat 🥵

My GF and I are visiting Ajaccio, Corte, Zonza and Porto Vecchio in mid July and we’re wondering what temperatures to expect? We’ve read horror stories of blistering heat approaching 40 degrees Celsius, is this the case for all the places mentioned? We’re going for day hikes to Lac De Melu and Lac de Capitellu as well as the Aguilles de Bavella loop. What temperatures should we expect on these hikes at these higher altitudes?