Evidence, says Zack Whittaker for Zero Day, of data disappearing from solid-state storage facilities, when the storage medium is unpowered for several days. Apparently, additional degradation takes place when temperatures rise...

The money quote:

"A recent presentation by hard drive maker Seagate's Alvin Cox warned that the period of time data is retained on some solid-state drives is halved for every 9°F (or 5°C) rise in temperature where its stored. That means if a solid-state drive is stored in a warm room, say 77°F (25°C), its data can last for about two years. But, if that goes up by a mere few degrees to 86°F (30°C), that data's retention period will be cut in half." via Zack Whittaker at Zero Day