Hood-mounted grill thermometers are generally accurate, but it's important to understand that they aren't designed to measure the temperature of your cooking surface. The vast majority of grill hood thermometers actually show the temperature of hot air closest to where they’re mounted on the inside of the hood, though Fire Magic Aurora and Echelon grills have grid-level probes that reflect just how hot the grates are. Because of the distance between the grill grates and most built-in thermometers relative to the burners, the grates are typically about 75–100 degrees Fahrenheit hotter than what the hood thermometer shows while grilling. We’ve even seen some grills with differences as high as 150 degrees.

If the thermometer is side-mounted or you’re using a probe that’s inserted at grid level, the readings will be fairly close to the temperature of your cooking grates. Thermometers on infrared grills are the trickiest of all to rely on because those burners produce heat that travels in straight waves until it hits food on the grill grates. No matter how your grill is configured, an infrared temperature gun is the only way to be completely sure of the heat levels on its cooking surface.

That being said, built-in thermometers are still extremely useful as a guide and for repeatability when grilling. For example, let’s pretend the best batch of burgers you ever cooked came when the hood-mounted thermometer read 450 degrees. Though that’s not the exact temperature of your grill grates, you know to target 450 degrees on the thermometer the next time you’re cooking burgers for the family.