The climate of Olympus is affected by its geographical location, size, strata and the exposure of the mountain slopes. Generally speaking, it has a Mediterranean climate, warm and dry in the summer and wet in the winter. For approximately seven months of the year it is covered in snow (from November to May). Mount Olympus has a high level of precipitation throughout the year in the form of snow in the winter and rain and hail in the summer. In fact, the level of precipitation on Olympus is 3 to 4 times higher than that in Athens or Thessaloniki (1100 to 1800 mm of precipitation a year, while in Thessaloniki precipitation is 500 mm and in Athens 400 mm annually). Half of the precipitation falls as snow and the other half in the form of rain and hail. The average temperature in the winter ranges from -20o Cto+10o C and in the summer from 0o Cto20o C, though this is not to say that there are not some exceptions that fall outside these ranges. Every 100 m up Mount Olympus the temperature drops by approximately half a degree. Thus, if at sea level the temperature is 20o C at, on Mytikas Peak (2918 m) the temperature will be approximately 5o C. Finally, strong winds are a common phenomenon on Mount Olympus and sometimes the wind reaches speeds of over 100 km per hour.