The occurrence of urolithiasis is closely related to the climate. In general, in dry climates, the body becomes dehydrated, urine volume decreases and urine becomes concentrated, which increases the risk of crystal urine formation. For example, soldiers in the German and British armies serving in North Africa during World War II were more likely to suffer from urolithiasis than they were back home. However, there is not necessarily a definite link between climate and the development of urolithiasis. In some countries with hotter climates (e.g., Ecuador and northern Peru), urolithiasis is very rare. There is also a relationship between high temperatures and the formation of urinary stones. Hot weather causes increased sweating, loss of large amounts of water, and highly concentrated urine, which promotes urine salt precipitation and leads to urinary stone formation. For example, the incidence of urolithiasis is high in countries located in the tropics and subtropics, as well as in some southern provinces of China. Urolithiasis is also closely related to the seasons. Generally, July to September is the high incidence of urolithiasis, and the incidence of renal colic is also higher; its incidence is less in winter and spring. In Kuwait, the number of urolithiasis is twice as high as other months in summer when the temperature reaches 50°C. In summer, the content of calcium oxalate crystals and oxalic acid in the urine also increases, which on the one hand is related to the loss of body fluids; on the other hand, it is related to the long sunshine hours in summer that make the vitamin D precursors in the skin more converted to active vitamin D and increase the absorption of calcium in the intestine. In addition, people are able to eat more fruits and vegetables in summer, which also increases the excretion of oxalic acid. In conclusion, the increased excretion of calcium and oxalic acid in the urine increases the saturation of calcium oxalate and facilitates stone formation. In recent years, the incidence of urolithiasis has also increased significantly due to the greenhouse effect, which has increased the ambient temperature. However, the relationship between the incidence of urolithiasis and climate is not very absolute. For example, the Netherlands is wet and cold, and the Mesopotamian highlands are dry and hot, but both are areas with a high incidence of stones. In some regions, the climate does not change much over the centuries, but the incidence of urolithiasis can change significantly over decades, suggesting that other factors besides climate are influencing the incidence of urolithiasis.