Although we can't concretely ID the grassy weed pictured from the photos alone, it looks like Bermudagrass, which can be very common in lawns. Management of that weed requires either physical removal (digging the patches out) or chemical (using a systemic herbicide like glyphosate), then repairing the area with new turf. (Sod is faster than sowing seed for this, though a bit more costly, but neither would establish well in this heat and drought, so waiting for early fall may be best in that regard.)

Miri