I've calibrated the drift of CAL pedestals with temperature using ground muon runs collected at cold and hot thermal balance periods of Observatory TVAC (NRL, Jan 2008).
The histogram of the coefficients of pedestal drift with temperature for all LEX8 and HEX8 channels is shown on the following plot:
If for some run we plot for each LEX8 and HEX8 channel the pedestal drift with respect to June 28 versus temperature coefficient for the same channel, we get the linear correlation with the slope equal to the temperature during this run - see the plot below for July 22:
By applying the same procedure to the set of 20 runs from the period June 28 - July 22 (~1 run per day), one can obtain the evolution of pedestal temperature vs day from June 28 (top plot):
On the bottom plot the real CAL temperature (average of all AFEE board temperature for the whole run) was subtracted from "pedestal temperature", showing the effect of pedestal drift NOT related to temperature variation.
This drift is negative and has the rate equivalent to the temperature drift ~1 deg ped week.