In the middle of June the weather can be quite nice with warm, calm days. However, we are in the middle of the Atlantic where the weather can be quite brutal. It can be anything between 10 – 25 degrees C. Wet or dry.
Water temperatures will be between 12 – 14 degrees C depending on where along the course. 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.
The water is salty, grease up well to avoid chafe. Like everywhere we can have wind, rain and un-seasonably cold. Make sure you bring clothes to handle this.
Check out this link for weather updates.