Don't put it in a cup of water, just change your cycle range. I have mine set at 6*F, and it'd probably be fine as high as 8* or even 10*.
By having it measure air, and with water (and other water-based liquids, like beer) having a much higher heat capacity, the larger range of air temperatures will translate into a small range of liquid temperatures.
On the other hand, if it was measuring water, the high heat capacity would cause much slower cycling, but all of your liquids would now experience the large temperature range. The air temperature would likely cycle by 20*-30* (just a guess), instead of 6*.
