Exercising outdoors is a great way to enjoy the sunshine and warmer weather of summer.

But you’ll need to take some extra precautions to stay safe.

Here are some do’s and don’ts for working out when temperatures climb.

DO: Stay hydrated

Drink plenty of water before, during and after your workout to prevent dehydration and help regulate body temperature. Nicole Thompson of the American Council on Exercise recommends slowly drinking water or sports drinks about four hours before exercising. Aim for 1 ounce for every 11 pounds of body weight – so 10 ounces for a 110-pound person or 20 ounces for a 220-pound person.

Weigh yourself before and after working out to determine how much fluid you need to replace. The Academy of Nutrition and Dietetics recommends drinking 2-3 cups of water for every pound lost.

“If you’re sweating heavily or exercising for more than 60 minutes,” the academy says, “sports drinks can help your body refuel and rehydrate more efficiently.”

DON’T: Drink products containing alcohol

Alcohol is a diuretic, so it contributes to dehydration.

Also, don’t rely on thirst as an indicator of hydration. “Drink water regularly throughout your workout, regardless of whether you feel thirsty,” Thompson said.

DO: Wear lightweight and breathable clothing

Choose light-colored and loose-fitting clothes made of moisture-wicking materials. This’ll help keep you cool and dry.

DON’T: Wear dark colors or heavy fabrics

Dark-colored clothing can absorb heat and trap it against your body, Thompson said.

DO: Wear sunscreen

The key number to look for on your sunscreen is the sun protection factor. An SPF of 15 filters out about 93% of UVB rays, according to the Environmental Protection Agency, while an SPF of 30 will filter out around 97%. Look for “broad spectrum” on the label to protect against UVA and UVB rays.

Apply sunscreen 15 or 20 minutes before going out (check the instructions on the label). Reapply every two hours – or more frequently if you’re sweating a lot. Don’t forget about your ears, lips and any bald spots on your scalp – they need protection, too.

DON’T: Work out during the hottest times of the day

The sun is at its strongest between 10 a.m. and 3 p.m., so try to schedule workouts for earlier in the morning or later in the afternoon. Remember, you can always work out inside and in an air-conditioned area if needed.

DO: Know the signs of heat-related illness

Symptoms of heat exhaustion include:

• Nausea and dizziness
• Headaches
• Feeling weak
• A weak or rapid pulse
• Cold, clammy skin

If you experience any sign of heat exhaustion, move to a cool place, loosen your clothing, put cool and wet cloths on your body or take a cool bath, and sip water, the Centers for Disease Control and Prevention says. Get medical help if your symptoms don’t go away after an hour, if you’re symptoms worsen or if you’re throwing up.

Symptoms of heatstroke include:

• A body temperature of 103° F or higher
• Hot, dry, bright red or damp skin
• Labored breathing
• A fast, strong pulse
• Headache, dizziness, nausea or confusion
• Loss of consciousness

Heatstroke is an emergency. If you suspect it, call 911 immediately. “It’s better to err on the side of caution when it comes to heat-related illness,” Thompson said, “as it can be dangerous and even deadly if left untreated.”

DON’T: Overdo it

“Adjust your workout intensity to account for the heat and listen to your body’s cues,” said Thompson, adding that it’s important to pay attention to heat and humidity levels. (See ACE’s chart on potential risks associated with heat and humidity at sh-m.ag/3zfPrje.)

She recommends shorter workouts when temperatures rise, which will allow your body to get used to the heat. Then you can gradually increase your time outdoors and exercise intensity.

“Listen to your body,” Thompson said. “If you feel dizzy, light-headed or nauseous, stop your workout and rest.”