What standards apply to the requirement for organizations to maintain blanket temperatures?

Any examples are for illustrative purposes only.

The Joint Commission is not prescriptive regarding the temperature setting for blanket warmers. 

Best practice would utilize evidence-based guidelines and recommendations by organizations such as but not limited to AORN and ECRI to determine optimal and safe temperatures for blankets to be warmed to.  Both AORN and ECRI recommend maximum temperature setting of 130 degrees Fahrenheit (54 degrees Celsius) for blanket warming cabinets

Blanket warming equipment should be:

• maintained in accordance with manufacturer's recommendations
• loaded correctly and not exceed the level or quantity specified by the manufacturer's instructions for use (over-loading can be a source of fire)
• only contain items that the warming cabinet was designed for, blankets and fluids are not to be commingled in a warming cabinet unless specifically designed for that purpose

Additional Resources
AORN eGuidlines, Warming Cabinets
ECRI Institute Continues to Recommend Maximum Temperature Setting of 130 degrees Fahrenheit for Blanket Warming Cabinets