Are there any temperature limits when using Stratus?

Yes.  The Stratus receivers are designed to be operated between 0° and 40°C (32°-104°F).  

A Stratus receiver will automatically turn off if the battery temperature gets colder than -20°C (-4°F) or hotter than 65°C (149°F) to prevent battery damage.

The battery is located in the bottom of the unit, so avoid placing on hot surfaces when able.