Santorini can be easily reached all year long as it is very well connected with many big cities in Greece either by sea or by airplane. There are flights connecting Santorini with Athens, Rhodes and Crete.
During summer months  there are connections with several foreign airports.
Ferries and high-speed catamarans depart from the port of Piraeus, in Athens. There are also  sea connections to ports of the surrounding islands including (Mykonos,Crete,Rhodes).

The majority of the year is sunny, with clear skies, making Santorini one of the most enjoyable vacation destinations. January, February and March have an average temperature of 12 to 13 C°.
The spring months of April and May are characterized by temperatures in the high teens. From June to September, Santorini weather is hot and temperatures are in the high 20s to the low 30s.
From October, the weather in Santorini begins to get cooler, with temperatures ranging from the low to high teens.
On the whole, Santorini weather is ideal year-round holidays. Even if the sea is too cold to swim in, the excellent weather conditions in Santorini make it possible to enjoy beachcombing, sightseeing and touring. The sunset is just as beautiful in the winter, as in the summer.