what is the effect of temperature on the receive sensitivity of the Xbee 868 PRO

I have found the sensitivity of the Xbee 869 Pro to diminish as the device becomes hotter - the effective range achieved between two devices at 300mwatt output setting reduces buy up to 50% when the device temp increases from 30deg C to 45deg C. Is this normal? Is there a way to set the channel center frequency to optimise, for example, RSSI, to obtain best receive sensitivity?

No that s not an option.