The later in the year, the more chance of a storm--for which you want to get off the beach until things calm down. Especially stay away from logs which the waves can roll on top of you (happens every year, unfortunately). That being said, September and early October are generally very pleasant. Do note, though, that even in midsummer the ocean water is COLD--surfers and more than casual waders generally wear wet suits when they go in. There are occasionally shirt-sleeve days at the beach--there were some in February when I was there--but most of the time it's more like the Atlantic in your part of the world.