The key characteristic of a Mediterranean climate is that the majority of its rainfall occurs during the winter months.
This is due to the shift of the Westerly winds southward during the winter, bringing moist air from the Atlantic Ocean to the Mediterranean region. This results in cyclonic storms that produce significant precipitation.
During the summer months, Mediterranean climates experience hot and dry conditions with very little rainfall. High-pressure systems dominate the region during this time, preventing cloud formation and precipitation.