Summer in Southern California means barbecues, beaches, and pool time. While we all know to protect ourselves during the summer season with sunscreen and extra water, people with certain chronic conditions need to be more cautious than most.

Some common medical issues, even when well controlled, can flare up in the sun and heat. And not just during long days outside—when it gets really hot and bright, normal activities can pose a risk.

"Often people are just running to the grocery store a couple blocks away when they run into danger," says primary care physician Dr. Marvin Mina. "For those with certain health conditions, that small exertion in that heat can already compromise you."

Find a Cedars-Sinai primary care location near you

Below, our experts outline a few conditions that can make you more vulnerable—and ways to stay safe and healthy this summer.

Migraines are agonizing headaches that can make you nauseous and sensitive to light. Dehydration can trigger a migraine, says nurse practitioner Fabiana Saad. So if you get migraines, be sure to drink extra water or electrolyte beverages while it's hot out.

During an attack, it's best to retreat into a dark, quiet room. If you have to go out, protect yourself from the brightness of the summer sun with a hat, umbrella, or polarized sunglasses.

Multiple sclerosis (MS) is a disease that affects the nervous system, causing vision problems, weakness, pain, confusion, and other symptoms.

Summer can be rough if you have MS—the worsening of MS symptoms when your body gets overheated because of time in the sun, exercise, or hot tubs is called Uhthoff's phenomenon. Saad says even a small increase in body temperature can aggravate symptoms, so if you're a multiple sclerosis patient, stay cool. Dress in lightweight, breathable clothing and have a plan to head indoors if symptoms get worse.

Autoimmune conditions like lupus and rheumatoid arthritis cause joint pain and fatigue. If you have one of these conditions, you should stay out of direct sunlight—UV rays can cause flare-ups, says Dr. Mina.

Stay indoors when the sun is brightest and always protect your skin with long sleeves and pants and broad spectrum, 30 SPF sunscreen made from zinc or titanium dioxide.

Read: 5 Fun-In-The-Sun Safety Tips for Kids

Rosacea is a common skin disorder that causes redness and bumps in the complexion, especially around the nose and cheeks. Sun can irritate rosacea, causing flare-ups, and heat can dehydrate the skin, making it even worse, says dermatologist Dr. Susan Rabizadeh.

Dr. Rabizadeh echoes Dr. Mina's warning that sun is absorbed into the body even during short times outdoors that might not seem significant. "It's not just when you're at the beach or the pool, it's when you're working in the garden or walking the dog," Dr. Rabizadeh says. "People get the most sun during routine activities."

Read: Everything You Need to Know About Bug Bites

Asthma, chronic obstructive pulmonary disease (COPD), and lung cancer are all conditions that make it harder to breathe.

If you have a lung condition, you might report more symptoms during the summer, probably because an increase in wildfires affects air quality, Dr. Mina says. "More fires mean dirtier air, which irritates lungs," he says. "In the summer, the environment gets less friendly for people with respiratory illness." Try to stay indoors during fire season, especially when you're exercising.