Make sure the water hangs around long enough to do some good. Mulches reduce evaporative losses. Additionally, they keep the soil cooler which is also helpful. The small size mulch grade pine bark chips are good looking, effective, and readily available. First weed, then water, finish with mulch.
Mulches are most effective when applied an inch or two deep.
If dry weather continues, move some mulch aside to check soil moisture, then recover. Home-made mulches such as coarse, chunky compost or shredded leaves are also good. Be cautious about grass clippings as mulch material. And you are better off using peat moss as a water-holding soil amendment than as a mulch. It dries and crusts to a moisture-resistant surface from which water runs as off a duck's back.