Valencia has a very pleasant Mediterranean climate, where winter comes and goes without being too traumatic for anyone. In the winter, temperatures tend not to drop below about 12 degrees, although a few colder days are normal.
Most of the annual rainfall happens in the spring, as the weather gradually seems to be improving before breaking into showers. July and August get hot, with temperatures pushing their way up to 35 degrees. Suncream is a good idea, especially for those first hot days.