Europe is the only continent without at least one desert region. To qualify as a desert, an area must receive fewer than 10 inches of annual rainfall.
There are many factors that contribute to the lack of a desert on the European continent. One factor is Europe's distance from the equator. Another is that there is a large presence of relatively warm water bodies surrounding the continent, including the Gulf Stream of the Atlantic in the north and the Mediterranean Sea in the south, that promote rainfall. Finally, the southern part of the continent is mountainous, and the humidity there attracts the vapors that cause the formation of rain clouds. While climate change may cause areas of Portugal to eventually be classified as desert, this is a distant concern.