Like JB said, the water starts getting better from Sept on as weeds and algae die back. Usually there is less rain and that helps too.
We've had some great trips in Dec and Feb so Bowfishing can be (and is for many of us here) a year round sport.
We wait for sunny days and then go out and look for flats that will catch the sun and hold the heat, drawing the carp.
Good Luck.