Some cookers have built-in temperature gauges and others don't. A word of caution regarding manufacturer installed temperature gauges....depending on the location within the cooking chamber they may be misleading and your bbq results may suffer.
You need to monitor cooking temperatures in your cooker at, or very near, the cooking grate location. If the manufacturer installed the gauge more than a few inches above the cooking grate, the temperature you cook at may not necessarily be the temperature you are hoping for.
Temperatures in a cooker usually will be higher when taken at higher levels within the cooking chamber. Try to monitor temperatures on the cooking grate, or as near meat level as possible.
In my Weber Smokey Mountain (WSM) smoker I use a 12-inch stem thermometer from a turkey fryer to monitor temperatures very near the cooking grate. It's cheap and it's easy, but most of all...I didn't have to drill holes in the cooker dome and risk cracking the coating on the cooker to install a gauge mounted in the dome lid. And for those that know me well, you can understand how painful it would be for me to "crack" the lid or "scratch" the finish.
From experience and prior measurement with a Taylor oven thermometer I know that the temperature on the bottom grate in this cooker averages about 20 degrees less than the temperatures on the top grate when I use the water pan, so if I'm cooking on both grates during a cook, I usually rotate the meat top to bottom about 1/2 way through the cooking process. This ensure that both cuts of meat finish at close to the same time. If using sand in the water pan, or if I leave the water pan empty altogether, the temperature might actually be hotter on the bottom grate than the top grate. It can vary from cooker to cooker and depends on a lot of factors, thus the importance of monitoring the temperatures closely.
It's also important that you monitor the internal meat temperature during the cooking process. As you can see in the picture above I use a digital unit purchased from a kitchen store. I have several of them made by various manufactuers including Polder, Taylor and Maverick.
As an aside, and in the spirit of shameless self-promotion, there are some nice digital thermometers advertised in the margin on the right hand side of this page if you'd like to help support my efforts here on the bbq blog. There are others advertised on my sister web site located at TheBBQGuy.com . For those of you that have purchased from me using the links in the past, please allow me to extend a heartfelt 'thank you'.
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