The weather in Crete can vary significantly from location to location. Although commonly considered to be a Mediterranean climate, that really only applies to certain low-lying areas. The country's weather is best described using three categories.
Dry Mediterranean: This covers the coastal areas of Greece, as well as most of the islands. Summers are ideal for beach vacationing, thanks to a predominantly sunny and dry forecast, with little precipitation. Winters are cold and generally quite wet. Some snow can fall, but it is very little and infrequent.
Alpine Mediterranean: This covers the very high altitude areas of Greece, such as the Pindus Mountain Range. Summers here are much cooler than in the lower-lying areas along the coast, and frequent thunderstorms bring plenty of rain. Winters are also much harsher, with heavy snowfalls for several months. Roads in this region are often closed due to snow, so any travel should be carefully planned.
Continental Mediterranean: This category applies to inland Greece--any places that are not near to the sea, yet are low in elevation. The weather here has slightly cooler summers than along the coast, yet they are still warm and enjoyable. You can expect slightly more precipitation here year-round as well. In the winter, it can get quite cold, dipping to freezing or even slightly below as times. Snow is certainly a possibility here in the winter months.
Crete is also home to very unique wind pattern called the etesians. They winds blow from May to October, although they are strongest and most common in the hottest months of July and August. They are much loved by locals thanks to their ability to significantly cool down the area near the Aegean Sea, which enjoys slightly lower temperatures than their neighboring locations, although they should have similar weather patterns. As the mercury rises, a nice breeze thanks to the etesians is well received!