In terms of weather the best time to visit Dubrovnik is during the months from April to September.
The temperature is in the mid to high twenties, reaching a height of mid-thirties in the peak season of July and August. Tourist numbers and prices increase greatly at this time with both domestic Croatian travelers and people from overseas visiting Dubrovnik. Sun protection and general precautions against the heat will need to be taken for your baby or toddler during the high season. The islands of the coast from Dubrovnik enjoy the most sunshine during the summer months. For a quieter, less tourist intensive experience in Dubrovnik go earlier or later in the year. For those travelers interested in skiing and other winter pursuits Dubrovnik can be a much cheaper base as you travel outside the city to slopes.