This snippet from the doc for cat6k running CatOS might give some idea:
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/catos/8.x/system/messages/emsg.html')">http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/catos/8.x/system/messages/emsg.html
Error Message SYS-2-TEMP_HIGHFAIL: Temp high failure
Explanation This message indicates that the internal temperature has risen above 50°C (122°F). This message applies only to the redundant supervisor engine in the switch.
Recommended Action No action is necessary. This message is provided for information only. If the temperature exceeds 70°C (158°F), the Temp Critical Failure message appears and the system automatically powers down after 5 minutes.
Other temp-related syslog messages:
SYS-0-SYS_TEMPMAJORFAIL: Chassis major temperature threshold exceeded
SYS-2-SUP_TEMPSHUTDOWN: System shutdown due to high temperature
reading on supervisor [dec]
SYS-2-SUP_TEMPSENSORFAIL: Supervisor temperature sensors failed,
please powercycle the system
SYS-2-SYS_TEMPMINORFAIL: Chassis minor temperature threshold exceeded