The region of the lowlands is coated with a thick layer of glacial elements (sand, gravel, clay) that covers more diverse relief of the older ground. Generally flat and wide bottoms of the valleys are padded with river settlements. Slopes of the hills over are coated with fertile clays and therefore, to begin with the Paleozoic era, they became the lands for people to settle and cultivate intensively. Later form of economy caused almost complete deforestation of the slopes. Not only fertile grounds, but also the mild climate is conductive to development of agriculture and market gardening. The annual average temperature of the Wrocław area is . Average temperature of the hottest month (July) is , and of the coldest month (January). The average amount of rainfall is , with its maximum in July and minimum in February. The snow layer disappears after 45 days. The winds, similar to those appearing in the West side of Poland, are West and Southwest.