Long before Thomas G. Masaryk became father and first President of the new, independent nation of Czechoslovakia, he wrote a doctoral thesis on suicide. Suicide and the Meaning of Civilization covers a whole spectrum of possible causes for this act, which, as the 19th century drew its final gasping breaths, was talked of as an epidemic in many European countries. I've been cheating a little by reading an English translation from 1970 (meh, I've got coursework to write), but the German version is available to read online here.
Masaryk's treatment of the subject, published in Vienna in 1881, comes across as a strange pick-and-mix bag; admissions that the available statistics are insufficient to reach conclusions amongst bold, unsubstantiated assertions. This is not all that surprising when you consider that at this time sociology was only just beginning as a discipline. The following are some of the statements I found less believable but hey, I'm not expert on the subject:
Chapter 2, Section 1
5. Wind. The wind and suicide are already related in the popular belief that strong winds rise whenever someone hangs himself. In any case, certain winds are pernicious, as for instance, the sirocco; Cheyne claims the fall and west winds are responsible for suicides in England, and Osiander makes the same assertion for northern Germany. But how hot, drying winds, or cold and damp winds exert their unfavorable effects is evident to all. Think, for example, how the drying winds of America cause a degeneration in the glandular system, which causes the striking difference between the Yankee and his Uncle Bull* and also in part his irritability.
6. […] Women, it is said, choose Sunday with relative frequency, no doubt for religious reasons; Saturday, as housecleaning day, allows them no time for dissatisfaction with life; Monday is also supposed to be very unpleasant for women.
7. With respect to time of day, most suicides are generally committed during the day, the fewest at night. Night has something soothing, life-giving, and restorative about it; also, most men are born at night, when the fewest deaths occur. The bright day excites and stimulates. While the darkness of night leads to understanding, peace of mind, and sleep.
(translation: William B. Weist and Robert G. Batson)
*John Bull, i.e. the English?