The climate in Greece is predominantly Mediterranean. However, due to the country's geography, Greece has a wide range of micro-climates and local variations. The Greek mainland is extremely mountainous, making Greece one of the most mountainous countries in Europe.[1] [2] To the west of the Pindus mountain range, the climate is generally wetter and has some maritime features. The east of the Pindus mountain range is generally drier and windier in summer. The highest peak is Mount Olympus, 2918m (9,573feet).[3] The northern areas of Greece have a transitional climate between the continental, the Mediterranean and the humid subtropical climate. There are mountainous areas that have an alpine climate. Also, various areas of Greece have semi-arid climates.[4] [5]
The climate of Greece can be divided into the following Mediterranean climate (Köppen climate classification: Cs) subtypes:
According to the Climate Atlas of Greece which was published by the Hellenic National Meteorological Service (H.N.M.S) the Mediterranean climate (Köppen climate classification: Csa) is the predominant climate found in Greece.[6] This climate occurs in the North Aegean islands, some of the Cyclades and most of the Dodecanese, Evia, some low-lying areas of Attica, the Ionian Islands and most of the western coast of the country, the eastern and southern low-lying Peloponnese areas, and the low-lying areas of Crete. During the summer, the weather is most frequently sunny and dry, and any precipitation falls in the form of showers or thunderstorms from cumuliform clouds. The air is usually hot during the day and pleasantly warm at night, but there are some very windy days, especially in the Cyclades islands and around them. Heatwaves may occur, but they are usually quite mild at the coastal areas, where temperatures are moderated by the relatively cooler sea and the sea breeze. Winters are wet and any snow that falls does not last long, especially in the south-facing slopes. Rain in winter is often persistent: The west areas of this climate zone receive a relatively higher amount of precipitation. Warm-summer Mediterranean climate (Csb) exists in roughly the same areas but in higher elevations (>1,000 m.), such as mount Parnitha in Attica.
In this climate type (Köppen climate classification: Csc) with much lower temperatures, the winter is harsh with abundant snowfalls, while the summers are cool with occasional thunderstorms. This climate is to be found on high mountains, like in the Pindus and Rhodope mountains, and predominantly the higher elevations of the mountains of Crete.[7]
This climate is classified as between humid subtropical and continental (Köppen climate classification: Cfa and Dfa) with strong characteristics of both the continental and Mediterranean climate.
According to the Climate Atlas of Greece published by the Hellenic National Meteorological Service and the network of the National Observatory of Athens, a hot semi-arid climate (Köppen climate classification: BSh) is found primarily in Piraeus and much of the Athens Riviera, areas of West Attica (Aspropyrgos, Salamina, Vlychada) and the Gulf of Corinth, most of the Cyclades, some islands of the Argo-Saronic Gulf (Aigina, Hydra), some areas of Crete (Lentas, Moni Toplou), Gavdos some islands of the Dodecanese (Kasos, Nisyros, Karpathos) and locally in Chalkidiki (Neos Marmaras).[4] [5]
Cold semi-arid climate (Köppen climate classification: BSk) is found in various areas of Macedonia and Thessaly, including the city of Thessaloniki, the second largest in Greece.[6]
Various areas of the country have registered temperatures over and below . The recorded by minimum/maximum thermometers in Tatoi and Elefsina on 10 July 1977 as reported by a communication of Dr. Athanasios D. Sarantopoulos was also the WMO record high temperature for Europe until 11 August 2021 (44 years).[9] [10] Average annual temperatures in Greece range from around in Kaimaktsalan up to almost [11] in Lindos. Summer average highs in Greece are the highest in the Evrotas Valley. Mainland Greece records a very high number of tropical nights reaching locally over 130 in Monemvasia while the islands can climb over 150 tropical nights in Kastellorizo. Winter average temperatures locally reach over 15°C in the Dodecanese and below -3°C in mountainous areas.[12]
Based on mean absolute minimum temperatures, plant hardiness zones in Greece vary from 6a to 11a.[13] Downtown Athens falls in 10a zone while the Athens Riviera falls mostly in 10b zone.[14] Thessaloniki straddles 9a/9b zones while areas in Macedonia may reach up to 10a zone (Great Lavra).[15] Zone 11a can be found in the Dodecanese, Crete, Cyclades and the Argo-Saronic Gulf, while Monemvasia in mainland Greece also falls in 11a zone.[13] [16] According to the Gouvas formula which adjusted USDA[17] plant hardiness zones for Greece, Kasos falls in 11b zone.[18] [19]
The table below provides USDA hardiness zones for selected areas from the data of the National Observatory of Athens and other public authorities.
| City | Zone |
|---|---|
| Kasos[20] [21] | 11a |
| Karpathos[22] | 11a |
| Kastellorizo[23] | 11a |
| Lindos[24] | 11a |
| Lentas[25] | 11a |
| Palaiochora[26] | 11a |
| Rhodes Port[27] | 11a |
| Falasarna[28] | 11a |
| Heraklion Port[29] | 11a |
| Plakias[30] | 11a |
| Amorgos[31] | 11a |
| Nisyros[32] | 11a |
| Hydra[33] | 11a |
| Monemvasia[34] | 11a |
| Koufonisia[35] | 11a |
| Patmos[36] | 11a |
| Spetses[37] | 11a |
| Sisi[38] | 11a |
| Sifnos[39] | 11a |
| Sitia[40] | 10b |
| Naxos[41] | 10b |
| Patras Port[42] | 10b |
| Lavrio[43] | 10b |
| Nea Smyrni[44] | 10b |
| Palaio Faliro[45] | 10b |
| Gazi, Athens[46] | 10a |
| Kifissia[47] | 10a |
| Arta[48] | 10a |
| Great Lavra[49] | 10a |
| Kalamaria[50] | 9b |
| Ippokrateios Politeia [51] | 9a |
| Nemea[52] | 9a |
| Serres[53] | 8b |
| Alexandroupolis[54] | 8b |
| Kaimaktsalan[55] | 7a |
| Vathistalos (doline) [56] | 6a |
In 2021, the government officials announced that they are considering giving the heatwaves names that could help people better prepare for more extreme heat[57] after the longest and most intense heat wave in recorded history affected the country from 26 July to 10 August of that year, during which many records that stood for decades broke.[58] Other notable heatwaves include the 2007 European heat wave as well as that of July 1987.[59]
In July 2023, another long lasting major heatwave struck the country with record breaking temperatures mostly in the eastern part of the mainland. The World Meteorological Organization station in Gytheio, Peloponnese[60] registered a staggering 46.4 °C (115.5 °F) which constitutes the highest value a National Observatory of Athens station has ever measured since records begun in 2006, and one of the highest values ever recorded in the country by any official institution. As a result of this heatwave, devastating fires[61] burned forested areas in southern Rhodes and Laconia[62]
According to the data of the network of meteorological stations which belong to the National Observatory of Athens, the lowest average annual precipitation in Greece is recorded in Schoinoussa with 240 mm (2013-2023) while the highest average annual precipitation in the country is recorded in Theodoriana, Epirus, with 2,529 mm (2009-2023).[63] Ioannina, the capital city of Epirus is considered to be the wettest city in mainland Greece with a population of over 50,000 inhabitants, receiving precipitation just short of 1,100 mm per year.[64]
Probably the most well known local winds in Greece are the etesians (also known as meltemia). With their name notating their annual fluctuation (έτος (étos) means year in Greek), these winds may blow from May to October, with their highest frequency being recorded in July and August. They keep temperatures and diurnal temperature fluctuations in the Aegean Sea lower than the respective ones found in the Ionian Sea or mainland Greece.[65]
According to the Climatic Atlas published by the Hellenic National Meteorological Service, Greece receives less than 1.600 hours of sunshine per year in mountainous areas of Epirus and more than 3.250 hours of sunshine per year in South Crete.[66]