So, for your hot and dry summer time, if you started those annuals that Rick mentioned above, they would very likely bloom well for you right through the hot weather if you can keep them watered enough. Nasturtiums are another nice flower that blooms well in hot, dry conditions. Plus the flowers and leaves are edible as well.
Once the rains started, the annuals would probably peter out, and some of the more tropical flowering plants like Pentas will do well.
Star Flower (Pentas lanceolata)
Scroll down the page on the above link to see a bunch of the different colors of these very durable flowers.