Snow falls in the city very rarely, although somewhat more often in nearby mountain tops. Throughout its history, the Central Valley of Mexico was accustomed to having several snowfalls per decade (including a period between 1878 and 1895 in which every single year—except 1880—recorded snowfalls) mostly lake-effect snow. The effects of the draining of Lake Texcoco and global warming have greatly reduced snowfalls after the snow flurries of 12 February 1907. Since 1908, snow has only fallen three times, snow on 14 February 1920; snow flurries on 14 March 1940; and on 12 January 1967, when  of snow fell on the city, the most on record. The 1967 snowstorm coincided with the operation of ''Deep Drainage System'' that resulted in the total draining of what was left of Lake Texcoco. After the disappearance of Lake Texcoco, snow has never fallen again over Mexico City.