Generally speaking, Dalmatia can be divided into two climate zones: Mediterranean and continental. Dubrovnik, has a typical Mediterranean climate.
Weather forecast from yr.no, delivered by the Norwegian Meteorological Institute and the Norwegian Broadcasting Corporation
Dubrovnik has hot and moderately dry summer, while the winters are mild and wet. Summer, especially July and August are the "high season" months on the coast and on the islands with an average temperature of 28°C and an average sea temperature of 24°C. If wondering when is the best time to go, May, June, September and October still have nice weather.
The sea is warm (18-20°C), although it is not unusual for a couple of continuous days of rain accompanied by the southern wind "Jugo" which locals blame their headaches on. In those months the prices are also a bit lower, but some services still/already go by winter schedules and working hours so, for example, ferry routes may be scanty.
Visiting Dubrovnik in Spring
Dubrovnik in spring is a fantastic time to visit, along with other destinations in Croatia. The city of Dubrovnik comes alive with an influx of visitors during Easter, drawing people from around the globe. In April, the country blossoms with vibrant colours, offering a picturesque landscape as spring reaches its peak. Whether you're exploring Dubrovnik or other parts of Croatia, spring promises a delightful experience.
Visiting Dubrovnik in Winter
Dubrovnik experiences mild winters, although it can get a bit chilly. Compared to other Croatian cities Dubrovnik maintains reasonably warm temperatures during winter. The daytime highs range between 7°C and 9°C, with average temperatures around 5°C. Nights can be colder, occasionally dropping to freezing temperatures in January.
Sunshine hours are limited during winter, with around five hours per day in December and January. However, they increase to seven hours per day in February, signalling the approaching spring.
Rainfall is relatively high in winter, although less than in autumn. The sea in Dubrovnik cools down significantly during winter, reaching a temperature of around 14°C. While not ideal for swimming or beach activities, these conditions are still preferable compared to the colder climates in northern Europe.