Except where shell-holes obstructed drainage, the ground in west Flanders dried quickly and became dusty after a few dry days. A 1989 study of weather data recorded from 1867 to 1916 at Lille, down the road from Ypres, showed August to be more often dry than wet, a trend towards dry autumns (September–November) and that average rainfall in October had decreased over the previous From 1 to 10 August, of rain fell, including in a thunderstorm on 8 August. In August 1917, of rain fell, of which fell on The month was so overcast and windless that water on the ground dried slower than usual. September had of rain and was much sunnier, the ground drying quickly, hard enough in places for shells to ricochet and for dust to blow in the breeze. In October, of rain fell, compared to the 1914–1916 average of and from there was another of rain and only nine hours of sunshine, little of the water drying; another of rain fell on 10 November.