Weather Yearly
Despite its small size, Greece has a varied climate. Most of the country, including all coastal areas, enjoys a so-called Mediterranean climate. Summers are hot and dry with a 7-month period of near-constant sunshine generally from April until November. The remainder of the year is characterized by a relatively cold, rainy period which generally starts sometime in November and lasts until late March or early April. Sporadic rains do occur during the dry season, but they tend to be rare. The country's Ionian Coast and Ionian Islands tend to receive more annual precipitation than the rest of the country. The islands in the southern Aegean and parts of the southeastern mainland are the driest areas of the country.The most pleasant weather occurs in May-June and September-October. The warmest time of the year starts in mid-July and generally lasts until mid-August, when the annual meltémi winds from the north cool the country.
Mid-July to mid-August is the height of summer, and the midday sun tends to get very strong.Summer evenings tend to be very rewarding. As strong as the sun may get on a summer afternoon, the low levels of atmospheric humidity in most areas of the country prevent the air from trapping much heat, and temperatures tend to dip to very pleasant levels in the evenings. Coastal areas near open waters, especially on many of the islands, tend to be quite breezy, and can be quite cold at night.While the Mediterranean climate characterizes most of the country, two other climate systems are present. One is the cool Alpine climate which is found on mountainous areas of the country's interior, including many high-altitude valleys. Another system is the Continental climate found on the interiors of north-central and northeastern Greece, and gives those areas very cold winters and warm, relatively humid summers.
Greece: The Weather and When is Best to Go
The best time to visit Athens and the Islands begins in May (when the mean temperature is 69 °F (21 °C) degrees and rainfall less than 0.6" (1.5 cm) and continues on through June (mean temperature 77 °F (25 °C) and rainfall less than 0.2" (0.5 cm)), July at a mean of 82 °F (28 °C) and rainfall less than 0.2" (0.5 cm) and September, with a mean temperature of 76 °F (24 °C) and less than 0.4" (1 cm) of rain.
The first two weeks of June have perfect, sunny and warm 80 degree (27 °C) weather, with little clouds or rain. Children are not yet out of school, so places are open and not crowded.
Suggestion:
Do your best to avoid traveling in August, since Athens, like Paris, belongs to the tourists: Some 60% of all Athenians take their summer holiday between the 1st and 15th of August. Stretches when it's well over 100°F (38°C) are not uncommon in August, when anyone with health problems such as asthma should be wary of Athens's nefos. The city can be very hot and exhausting -- and most tourist locations include lots of steps over dry, hilled areas.Most rain falls between November and February, when Athens can be colder and windier than you might expect. Average daytime temperatures range from 52°F (11°C) in January to 92°F (33°C) in August.Before you leave, run to the pharmacy and purchase a bottle of "Ocean" sodium chloride for each person in your traveling party, and lip balm. The air, especially in Athens is very dry---think Arizona or Denver, and a squeeze of these nose drops a few times a day can improve your trip considerably.
Island Weather
The weather in the Islands is about 10-15 °F (6-8 °C) cooler than Athens, and after watching the beautiful sunset, it gets chilly and cold. Be sure to pack a warm sweater and windbreaker jacket for the cool evenings and waterfront locations.
The weather on Crete is almost all year mild and sunny. Nights are cooler but in the day time you may find yourself on the beach or making a nice walk in your shorts. Accommodation is available, but choose for a city like Chania or Rethymno, so you can enjoy also nice evenings in good restaurants or do some shopping.
More activities are continued in the winter. Like walking with guide, small mini coach ecursions, scuba diving, horse riding, cooking and painting lessons etc.etc.