When you cook food at home, you know you have two hours—arguably four if you really want to push it—to get your food out of the room-temperature air and into your belly. Any longer, and that plate of chicken salad is a big ol bacterial brouhaha. But if you’re picnicking in 90 degree weather, food goes bad faster—a lot faster.
In the sweltering heat, you only have one hour to work with. That means your fruit salad should stay in the cooler until dinnertime, and your just-cooked barbecue shouldn’t sit out on the picnic table forever, either.
Food safety expert Ben Chapman ran the numbers on the one-hour rule, expecting it to be overly cautious. But it turns out that Salmonella bacteria easily multiply tenfold in a little over an hour at 92 degrees. Another common food poisoning germ, Staphylococcus aureus, takes a bit longer—one and a half to two hours. Either way, if you were using the same two-hour rule that applies indoors, you’d have a chance of making yourself sick.
First, know which foods are the ones prone to going bad in the heat. Spoiler: it’s most of them. That includes cooked vegetables, cooked grain dishes (like rice), and meats. Low-acid fruits, like cantaloupe, also need to stay chilled if they’ll be on the table a while.
Here’s what Chapman recommends for picnicking without making yourself and others sick:
This might disrupt your usual cookout routine, but it’s all very doable with a little planning ahead. If you’re barbecueing away from home, book a picnic pavilion near the washrooms and pack a cooler and a bunch of ice to transport your goodies and to take home leftovers. You’ll be glad you did, when you’re heading home sans food poisoning.