If you are looking for a place to spend your holidays, you can't pick a better location than Athens, the capital and largest city of Greece and one of the world's oldest cities. Today a cosmopolitan metropolis, modern Athens is central to economic, financial, industrial, political and cultural life in Greece.
Athens climate is typical Mediterranean subtropical climate with long, hot and dry summers and mild wet winters. Summer season usually last from June to September with very little rainfall. Daytime temperatures during summer months can reach up to 35°C with sunshine all day long. The hottest month is usually July with average temperature of 27°C but the best month to swim is August when average sea temperature is 22°C.
Probably the best time to visit Athens is Spring and Fall, there are lot of sunny days and warm temperatures but there are not so many tourists and you will probably go cheaper with the hotels and transportation. During spring temperatures are at steady 20°C and more with very little rainfalls. In the autumn or fall months temperatures go as high as 20°C but you should be aware of the sudden and heavy rainfalls that go away very fast but if you are not prepared you can be soaked to the skin.
Summer season usually last from June to September with very little rainfall. Daytime temperatures during summer months can reach up to 35°C with sunshine all day long. The hottest month is usually July with average temperature of 27°C. Have in mind that temperatures in august are so hot that most Athenians leave the city for the seaside or little villages on Greece many islands to escape the heat.
Winter is worst time to visit Athens and still, it is not bad time to visit it. You will have a opportunity to explore the city without many tourist and crowds around you. The temperatures in winter are averaging from 5°C to 8°C but they can go up to 15°C on some days. Snow falls very rarely in Athens, usually once per year and it is very light snow that melts very quickly. December is the month with most rainfalls, some 70mm of rain in month which is not high at all.
To summarize, Athens is a year-round destination. The most popular time to visit is late spring through autumn, when the weather is at the best for traveling. Summer is great, but the temperatures are a bit high and you will have to deal with lots of other tourists.