Extreme Heat Propane Safety - When extreme heat hits, follow the safety do's and dont's in this education brochure provided by the Propane Education Research Council (PERC). The extreme heat referred to in this brochure is not likely to be present in North Carolina, but there have been a few cases where propane containers that were overfilled released propane on a very hot or sunny day, causing injury and property damage. This a likely problem for any cylinder not upright.