In an effort to ensure accuracy and reproducibility in physical stability testing, temperatures of incubators used in several laboratories were monitored. Temperature tracking devices were placed in cans filled with 5% ethanol, then the cans were seamed. One can was placed on the top shelf of each forcing 38 C. incubator, while another was placed on the bottom shelf. After eight days, the cans were moved to analogous positions in the incubators used to cool the samples to -1 C. and form the chill haze to be measured. After another eight days the temperature monitors were removed and the data were analyzed. Temperature results were plotted and compared. Results showed that, in some cases, there were temperature gradients within the incubators, inaccurate temperature displays and temperature variability. At the same time, controlled studies were conducted in the laboratory to determine what temperature variation was sufficient to produce statistically significant changes in the physical stability measures. Recommendations for correcting the discrepancies will be given.