In the end of September, day time temperatures are usually around 15 degrees C.
Water temperatures will be between 13 – 18 degrees C. Make sure you dress accordingly and consider wearing something under your wetsuit if you tend to get cold on the long swims. Use a Neoprene cap if you are not used to cold water.
Like everywhere we can have wind, rain and un-seasonably cold weather. Make sure you bring clothes to handle this.