Autumn is one of the best times of the year for taking photographs. The light is softer because the sun angle is lower. Even during the middle of the day which is the worst time to shoot, the lower sun is much better.
For me, when I'm doing family portraits, I can shoot later in the morning or earlier in the afternoon. This helps with the flexibility with clients. In Summer, the mornings are out because the best photographic light is at about 5.30am. You don't want to be asking your customers to get up that early!
Also the temperature is much cooler which is good for your client's comfort (and your own) as well as producing a better result in your images with a more natural skin-tone and less perspiration. Lastly, the wind is much less so place like the beach which tend to be a little tricky, come into play a good location.