Ithaca, where it lies

The climate of Ithaca, Greek island of the Ionian Sea, is Mediterranean, with mild and rainy winters, and hot and sunny summers. In the plains, the average temperature of January is 11.5 °C (52.5 °F), that of August is 25 °C (77 °F).
Here are the average temperatures (recorded in Argostoli, in the nearby island of Kefalonia).
Ithaca - Average temperatures
Min (°C)9910111518202119161310
Max (°C)141416182326292927231916
Min (°F)484850525964687066615550
Max (°F)575761647379848481736661

The rains amount to about 700 millimetres (27.5 inches) per year, and are concentrated in the period from October to April, while in summer it rains very rarely.
Here is the average precipitation.
Ithaca - Average precipitation

In the interior there are hills, culminating in Mount Nirito, 800 metres (2,600 feet) high.

Vathy from above

Winter, from December to mid-March, is mild but rainy, especially in December and January, when 100/110 millimetres (40/43 inches) of rain per month fall. However, there is a moderate amount of sunny days. Sometimes a cold wind from the north can blow, and the minimum temperature in the plains can reach 0 °C (32 °F).

The spring, from mid-March to May, is mild; rainfall becomes gradually rarer over the weeks, and fine weather becomes more and more frequent. May is a good month, before the summer heat.

Summer, from June to mid-September, is hot and sunny: the maximum temperature often exceeds 30 °C (86 °F), and can even reach 35 °C (95 °F), especially in July and August; at worst it can touch 40 °C (104 °F). Luckily, sea breezes blow, providing relief, at least when the heat is not excessive, and in any case you can cool yourself down in the sea.

Autumn, from mid-September to November, is mild (initially even quite warm) and rainy. In October, there may still be many sunny days.

Beach at Ithaca

The amount of sunshine in Ithaca is great in late spring and summer, when clear skies prevail, while from November to mid-March, sunny days alternate with periods of bad weather.
Ithaca - Sunshine

The temperature of the sea in Ithaca is high enough for swimming from July to September, while in June it is still a bit cool, around 22 °C (72 °F), but basically acceptable.
Here are the average sea temperatures.
Ithaca - Sea temperature
Temp (°C)161515161822242625221917
Temp (°F)615959616472757977726663

When to go

The best time to travel to Ithaca, for swimming and sunbathing, runs from June to mid-September.
For excursions in the island, the month of May or the first half of October are preferable, to avoid the heat that sometimes occurs in summer.

Back to the Ionian Islands.