A forced air should not have a wide variety of temps and my 1588 tests the same everywhere. You want about 100F for a forced air but you should not try to get a 1588 to match a certain thermometer unless you have a very impressive thermometer that you know is completely accurate. Instead wait until they hatch and see if they are on time or late and adjust accordingly before trying again. You'll actually get the temp more accurate faster waiting for each hatch than if you keep trying to match most thermometers. Very few have thermometers that are very accurate and some can be off by many degrees. Even when they aren't off most still have a 1-2degree error margin and that's enough to put your hatch off by a day.