Picture this: It's a perfect summer day. You're enjoying the time with family and friends, a cold drink in hand. As you take in the moment, your eyes linger on the food spread. How long have those burgers been sitting out? Should you be worried about that coleslaw baking in the sun?

Summer is a time for picnics and barbecues at the park, pool, beach or in your backyard, but it's also when the weather is at its hottest. The heat doesn't just pose a risk to your own health, it can also affect the safety of your food.

"The types of bacteria that cause foodborne illness, such as Salmonella, E. coli and Listeria, thrive in these warmer temperatures," warns Lea Obeid, a dietitian at Houston Methodist. "This means you will need to take proper precautions with perishable food you bring outdoors in the summer."

The CDC estimates that food poisoning results in 48 million illnesses each year, with exposure to unsafe temperatures being a top reason for foodborne disease.

Obeid shares another startling fact: Food doesn't need to look or smell bad for it to be spoiled by harmful bacteria.

Is your food sitting in the danger zone?

Unfortunately, we're not talking about the Top Gun song. The "danger zone" for food safety refers to the temperature range in which bacteria grows most rapidly — between 40°F and 140°F.

"When perishable food sits in this range, bacteria can double in number every 15 to 30 minutes, significantly increasing the risk of foodborne illness," says Obeid.

How long can food stay in the danger zone before it's unsafe to eat?

• Two hours if left at a temperature between 40°F to 90°F
• One hour if exposed to temperatures above 90°F

This means that, as the day heats up, the steps you take to keep perishable food safe to eat become more critical than ever.

What foods are considered perishable?

Generally speaking, perishable foods are those that require refrigeration. Nonperishable foods, on the other hand, are those that are shelf stable and can sit in your pantry for long periods of time.

Common perishable foods include:

• Meat, poultry and seafood
• Dairy products, including milk, cream-based items and yogurt
• Eggs, mayonnaise and egg-based dishes, such as egg salad and deviled eggs
• Cooked foods, including pre-prepared meals and leftovers
• Deli meats and sandwiches
• Certain fresh fruits and vegetables, such as berries, leafy greens, tomatoes and mushrooms
• Fresh juices
• Soft cheeses, including ricotta, cottage cheese, Brie and mozzarella
• Prepared salads, such as potato salad, coleslaw and pasta salad

When outdoors, take care not to let these food items sit longer than an hour.

"Keep it hot, keep it cold, or don't keep it all," recommends Obeid.

Tips for keeping food safe in the heat

From brisket and potato salad to sandwiches and fresh fruit to those margaritas you brought along, you're not alone if you've noticed that the list of perishable foods contains many picnic favorites.

Not to worry. Here are tips for keeping perishable food safe in the heat:

Use coolers and ice baths. Safely transport and store food in a well-insulated cooler packed with plenty of ice or ice packs. At serving time, place dishes in bowls of ice to help keep cool foods cold.

Serve off the grill. By eating foods right off the grill, you enjoy more than a hot, fresh meal — you enjoy peace of mind that the food hasn't reached the danger zone is an added benefit.

Eat within the hour. You might be tempted to leave a food spread on the table for people to snack on as the day passes, but this can quickly become unsafe in the summer sun. Eat any perishable food items as soon as possible and promptly store any leftovers.

Use a food thermometer. This cooking tool can come in handy beyond your initial internal temperature check. You can use your food thermometers to monitor the temperature of food sitting out, ensuring you take action before it reaches the danger zone.

When in doubt, toss it out. If you're uncertain about the safety of a food item, it's best to be cautious. This is especially true for those at higher risk of getting seriously ill from food poisoning, groups that include infants and young children, older adults and people who are pregnant or immunocompromised.

And, of course, the same food safety basics you follow indoors still apply outdoors, such as:

• Wash your hands before handling food
• Wash veggies and fruit before chopping and eating
• Keep raw meat, poultry, seafood and eggs separate from veggies, fruit and cooked food
• Cook meat, poultry, seafood and eggs to the correct internal temperature
• Wash your hands after handling uncooked meats
• Serve food on clean plates and use clean utensils