I am setting up the 3rd bator as a hatcher -- put in a new wafer t-stat and replaced the drowned pc fan. Since I have had wide ranges in temp with my various thermometers I decided to check them against medical thermoms using the 'Jar-of-water-in-the bator for 24 hours' method ourtlined here [somewhere]. Just checked them.
My temps on the thermometers: Reg-99* & 100.5* On the digitals: 101.6* & 100* [this one doesn't measure 10ths]. Then I opened the hatcher, took out the jar of water and checked it w/my medical thermometers: 96.2*
I haven't had good luck with the medical thermometers. I would say that your temps are probably OK, since the other thermometers are all pretty close. I have a digital indoor/outdoor one and keep the little wireless outdoor receiver right in the bator and keep the indoor portion and put it where it is convenient. This thermometer also measures humidity so I can keep track of the humidity both in the incubator and in our house. It will tell you the minimum and maximum temperatures for each day so you know if you had any temperature spikes or power outages. It has really cut down on the temperature stress level that I experience with every batch because I know exactly what is happening each day. Knock on wood, I have had excellent results with this system, and by hatch rates have almost all been 100%. Hopefully I am not jinxing myself here since I have 31 eggs that I am putting in today. I am playing with the temps on mine to get it set up right now. I had goose eggs in it last and am trying to get the chicken egg temperature right again now. I have a still air, so I need to get it to run a little warmer again since the eggs are further from the heating element than the goose eggs were.