Koeppen's classification of world climates

Köppen codes are meaningful sequences rather than arbitrary abbreviations. The first letter identifies the broad thermal or dry climate group, such as A, B, C, D, or E. The second letter usually describes precipitation seasonality, such as f, s, or w. In three-letter codes, the third letter gives an additional temperature characteristic, especially the nature of summer or winter.

Köppen classification relies primarily on the long-term monthly pattern of temperature and precipitation. Monthly mean temperatures reveal the thermal group and seasonal thresholds, while monthly precipitation totals show whether rainfall is year-round or concentrated in a dry summer or winter. Daily maximum temperature, wind direction, and soil moisture may be useful for other studies, but they are not the core data for assigning a Köppen code.

Koeppen classification does not depend only on the total annual rainfall. It also considers the monthly pattern of precipitation, the season in which rain falls, and temperature thresholds such as mean monthly temperature. Therefore, two places with equal yearly rainfall can have different moisture regimes and temperature conditions, placing them in different climate classes.

The Mediterranean climate is characterized by hot, dry summers and mild, wet winters. Subtropical high pressure suppresses rainfall during summer, while the seasonal shift of westerlies and frontal systems brings winter precipitation. This distinctive seasonal reversal of rainfall makes option A the correct identification.