I have a #1, analog. I check ambient temp with my Maverick ambient probe, or Fireboard ambient probe. Most of the time, I don't even use an ambient probe. Temp swings are not an issue, and as long as something doesn't seem totally out of the ordinary, I don't see a reason to obsess about ambient temp. My analog #1 is going to have temp swings + or - 20 degrees or more above and below my dial setting. And that works just fine in the world of low and slow. And for salmon smoking, I do a 15 minute on, 45 minute off rotation to control the box temp. If you have a D model, you can use your controller for your ambient temp reading, but if you doubt it, add another probe such as Maverick, Fireboard, or numerous other options. It's always good to have something as backup to your built-in probes anyway in my opinion.