From the forum's caresheet:
TEMPERATURE
~80F (ambient temps)
~90F (basking temps)
75 or below is unhealthy
Night drops in temps are not necessary or desired
Maintaining proper temperatures is essential to keeping your ball python healthy – failure to do so can lead to a host of issues from poor feeding to potentially lethal respiratory infections. For this reason you want to make sure you are able to measure the temperatures accurately. The sticker-type thermometers used in aquariums, and the little dials usually found in pet stores are routinely inaccurate and do little more than measure the temps of the glass to which they are adhered. Do yourself and your ball python a favor and invest in a digital thermometer. One of the most cost-effective and easily available is the Accu-Rite digital thermometer/hygrometer combo available at large stores such as Wal-Mart. These retail for less than $15 and include a probe making it possible to monitor the warm side and cool side temps as well as the humidity levels all simultaneously.