The bladderpod shrub I can see from my window has had abundant yellow flowers nearly year-round. Other California native plants from chaparral and desert areas can also have a long bloom time. What sets these particular plants apart is that they grow in full sun, need excellent drainage and will thrive in the hottest part of your garden.
Desert plants can benefit from the reflected heat of a south- or west-facing wall, an adjacent sidewalk or a big boulder that absorbs and radiates the heat of the day. Using a mineral mulch such as gravel or decomposed granite instead of an organic mulch such as arborist chips can also help these plants to thrive.