The summer months are generally the best time to dive in Greece. In this Mediterranean climate, expect hot and dry summer weather from July to September, with average temperatures of 27°C/80°F. Winter temperatures drop to an average of 6°C/43°F. Water temperatures range from 16-23°C/60-74°F, depending upon the site, sea and island. You'll want to research your particular destination, so you come prepared with the proper thermal gear. In terms of visibility, you'll be able to see from 6 metres/20 feet to more than 50 metres/165 feet, depending on the area and time of year.