I'm in Arizona, USA and I have had two bad viscous clutches, one stuck off and one stuck on. With the one stuck off, it would overheat on hills, reaching above 110 C. With it stuck on, it would be about 80C and make a lot of noise.
With a good Febi Bilstein viscous clutch, it hovers around 88 C and gets up to 108 C on the worst climbs with outside temps about 40+ C. I'm calling that "normal".
Regards,
Mark