The atmospheric pressure changes may cause temporary water level fluctuations of 1 foot or more. The information is given in whole inches above or below chart datum. The following currents are based on the averages of water flow through the entire cross section of the river, that is, from bank to bank and from the surface to the bottom during normal water flow conditions. The current encountered at mid stream is usually about 1.5 times the average velocity. Greater velocities may be expected when the difference between lake levels is greater, or when lake stages are higher.
Strong winds are most likely during fall and early spring.
However, extremes often occur in squall lines or thunderstorms. Winds along the river blow mainly out of the SW and W, but others are common. In spring and summer, N through E wind are frequently encountered as are northwesterlies and southerlies in fall and winter. The lower part of the Detroit River, below Fighting Island, is generally the shallow and has the same freezing characteristics as the W end of Lake Erie, forming an average thickness of 7 inches and an average maximum thickness of 11 inches. This ice generally starts to clear by mid-March because of the temperatures and the prevailing W winds.