Sheri... Likewise my condolences as well. Our waters off Catalina have been fairly warm the past few months. Recent temps have been no colder than 57 at depth in my experience. While hypothermia is possible (I don't know your brother's body type or BMI), I often do 3-6 dives in a day without any noticeable problems.
Please pass on our condolences to the rest of the family as well.
Please pass on our condolences to the rest of the family as well.