Sentence:  Aurora's orange sun (Baley scarcely noted the orange tinge now) was mildly warm on his back, lacking the <WSD>febrile</WSD> heat that Earth's sun had in summer (but, then, what was the climate and season on this portion of Aurora right now?). 
Meaning of the word marked with <WSD> tags:  Feverish, or having a high temperature.