Yes, that is very common with prednisone. It will get better as you lower your dosage.
I've run a 103 fever with a bad flare before. That particular case I ran a fever for a month straight, it went from 99 one week, 100 the next week, 101, 102, and then up to 103. Thought I was going to die, and i was goin to the bathroom 45 times a day and it was mostly blood. My joints always get sore and stiff during flares.
Flares can be mild or downright brutal. And each time they might hit you a different way so its sometimes hard to tell if its a flare coming on, or just some other illness like a cold.
UC since age 22, now 27. Several huge flares since then.
Currently tapering prednisone(35 mg from 80 mg). Also just starting 6mp again and lialda. I definately am not liking these drugs. Maybe surgery one day?