Snow covers the ground more often than not from Christmas into early March, but periods of bare ground are not uncommon. Lake-effect snow occurs when cold air crosses the relatively warm lake waters and becomes saturated, creating clouds and precipitation downwind. The location of these snowbands is determined by the direction of the wind. Due to the prevailing winds, areas south of Buffalo receive much more lake-effect snow than locations to the north. The lake snow machine can start as early as mid November, peaks in December, then virtually shuts down after Lake Erie freezes in mid to late January.
Spring comes slowly to the Buffalo area.
The ice pack on Lake Erie does not usually disappear until mid April and the lake remains chilly through most of May. As the prevailing flow is southwesterly, areas near the lake are often as much as 20 degrees colder than inland locations. Fortunately, the cool lake waters act as a strong stabilizing influence, so areas near the lake shore, including the city of Buffalo, experience more sunshine and fewer thunderstorms than inland areas. The cool air from the lake also retards the growing season, but this diminishes the threat of damaging late spring frosts. The average date of the last frost is near the end of April in the Buffalo metro area, but in mid May well inland.