As Faith stated, our flares are as different as the disease is for each of us. Some people get very bad rashes due to the sun and their lesions worsen. Some people feel extreme fatigue, nausea and increased joint and muscle pain. Your flare will depend upon the severity of your disease. The unnoticeable problems might be the fatigue, the muscle soreness, the joint stiffness, etc. All flares do not represent themselves as something that can be seen, they may be something that is felt!
Do take precautions when you are in the sun. Faith gave you some good suggestions. Don't forget to wear a hat, sunglasses and plenty of sunscreen with a minimum of 30SPF!
Peace and Blessings
Look For The Good and Praise It!