Map from Google - Corfu

The climate of Corfu (or Kerkyra), a Greek island in the Ionian Sea, is Mediterranean, with mild and rainy winters, and hot and sunny summers. The average temperature of January is 9.5 °C (49 °F), that of August is 25 °C (77 °F).
Here are the average temperatures.
Average temperatures - Corfu
CorfuJanFebMarAprMayJunJulAugSepOctNovDec
CorfuJFMAMJJASOND
Min (°C)5679131618191713107
Max (°C)141416192428313128231915
Min (°F)414345485561646663555045
Max (°F)575761667582888882736659

In the interior there are some hills, whose highest point is Mount Pantokrator, 906 metres (2,972 feet) high.
The rains are quite abundant, given that they amount to 800 millimetres (31.5 inches) per year along the coasts, and even more in the inland hills, and follow the Mediterranean pattern, with a maximum in autumn and winter, while from June to August it almost never rains.
Here is the average precipitation.
Average precipitation - Corfu
CorfuJanFebMarAprMayJunJulAugSepOctNovDecYear
CorfuJFMAMJJASONDY
Prec. (mm)959010065351510208075120120825
Prec. (in)3.73.53.92.61.40.60.40.83.134.74.732.5
Days121211963237101313101

Winter, from December to mid-March, is quite mild, even though it is not as mild as in the southern islands of Greece; moreover it is rainy, especially in December and January, when even 120 mm (4.7 in) of rain per month fall; in some years the rains are plentiful. However, there's no shortage of sunny days. Sometimes there may be outbreaks of cold air from the Balkan Peninsula, with some cold and windy days, and possible slight frosts at night. In inland hills, it can even snow.

Spring, from mid-March to May, is mild; the rains are quite frequent at the beginning, but then gradually become rarer, and fine weather becomes more and more frequent. May is a good month, before the summer heat.

Summer, from June to August, is hot and sunny: the maximum temperature exceeds 30 °C (86 °F) with some frequency, and can reach 35/36 °C (95/97 °F), especially in July and August; at the 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. This part of Greece, overlooking the Ionian Sea, is outside the area where the annoying but cooling Meltemi blows, therefore, the sea is warmer (see below).

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

Corfu

The amount of sunshine in Corfu is great in summer, when blue skies prevail, but it is also good in spring, when days with clear skies are already frequent. On the contrary, from October to March the amount of sunshine is not high, because sunny days alternate with periods of bad weather.
Sunshine - Corfu
CorfuJanFebMarAprMayJunJulAugSepOctNovDec
CorfuJFMAMJJASOND
Sun (hours)444791112119644

The temperature of the sea in Corfu is warm enough for swimming from July to September, while in June it is still a bit cool (22 °C or 72 °F), but all in all acceptable. Here are the average sea temperatures.
Sea temperature - Corfu
CorfuJanFebMarAprMayJunJulAugSepOctNovDec
CorfuJFMAMJJASOND
Sea (°C)151414151822242524221916
Sea (°F)595757596472757775726661


The best time to go to Corfu, for swimming and sunbathing, runs from June to August, although the weather is often good also in the first half of September.
For hiking and walking across the island, you can go from mid-April to mid-June, to avoid the heat that can occur in high summer.

Back to the Ionian Islands.