I will routinely be asked why so many people in Tennessee form kidney stones. While each person has his or her own reasons why he or she developed stones, many times the cause is attributed to dehydration from the warm climate.
Several studies have been performed to determine IF a true difference in the incidence of kidney stones between the different areas of the country. In 1994 the Journal of Epidemiology did in fact show that differences in sunlight exposure and ambient temperature contribute to kidney stone incidence. The percent of individuals with kidney stones was found to be in those individuals living in the Southeastern section of the United States -- lucky for us here in Tennessee!
Interestingly, no difference was seen between people based on what fluid they would drink (ie. tea, cola, etc.).
Similarly, recent studies into global warming have shown an increase in the incidence of kidney stones. With warming temperatures, the percent of individuals with this disease is expected to increase. For example, the "stone belt" is expected to include the Midwest by 2095 in one study.
If you are interested, the study can be reviewed at: http://aje.oxfordjournals.org/content/143/5/487.full.pdf