The electrical charge stored in a flash memory cell degrades over time, and will degrade much faster at extended temperatures. This degradation has been modelled to follow the Arrhenius Equation, degrading exponentially as temperature rises.
JEDEC Solid State Technology Association, an independent semiconductor engineering trade organization and standardization body, defines two specifications applicable to SSD endurance. The JEDEC specification for commercial flash SSD devices call for a client class SSD device to maintain a bit error rate (BER) of 10-15 or less, and retain data for minimum of one year at 30°C. The JEDEC spec also defines the data retention at elevated temperatures, but the retention time is quite alarming. Per JESD218, a client class SSD must maintain its data integrity at the defined BER for only 500 hours at 52°C (less than 21 days) or 96 hours at 66°C (only four days).