The early-blooming winter annuals can create an incredible display, but do so only rarely. Later-blooming species bloom more dependably, but mostly not in great masses of color. The progression of spring bloom des-cribed below is for average years near Tucson. It may be three weeks earlier or later depending on weather, elevation, and latitude. This event may occur between late February and mid April, usually in mid March.
Annuals are highly dependent on rainfall.
Massive and widespread displays occur only about once a decade, when the winter rainy season is both earlier and wetter than normal. Good shows happen in localized areas every three or four years. Seeing one requires being able to travel on short notice, and perhaps great distances. Death Valley may be spectacular in a year when Organpipe Cactus National Monument is poor. The high Mohave Desert may peak two or three weeks later than the lower elevation and more southerly Sonoran Desert.