The EM250 and EM260 have been fully characterized over Temperature and Voltage variation.
In general the chips perform better at colder temperatures than warmer – for both RF and DC characterization. There will be ~5 dB variation in RX Sensitivity and TX Power over temperature. (All values in the Datasheet are at Room Temperature. You can expect a worsening (of about 3dB) at +85C and an improvement (of about 2dB) at -40C. The TX EVM will be worse at +85C than at room temperature, but it should be below the 35% limit.
The Voltage Regulator is trimmed to 1.74V at room temperature and it will vary to 1.76V at -40C and 1.72V at +85C.
Current consumption will increase at +85C (by about 1mA) and decrease at -40C (by about 1mA) from typical values.