It sounds to me like your car is OK, but on the "high" side of normal temps. As long as it never gets over 110C, or consistently over 105C (i.e., not passing someone), I wouldn't lose any sleep. Check the fan clutch like Peter said. If yours is original (metal fan blade) it's probably due for replacement, ot at least a good cleaning. A lot of gunk builds up on the face and can keep the flat, diamond-shaped bimetallic spring from "engaging" the clutch at 105C (or whatever temp it engages at - I can't remember right now.) If you clean it, DO NOT remove the spring! Just use solvent, rags, a toothbrush, compressed air, etc as long as it doesn't deform the spring. Otherwise you'll be buying a new fan clutch for $250+.
Now, if your car runs hot at idle, with the A/C on, on a hot day (100F)... say 105-110C... your radiator is highly suspect. The car really should stay under 100C under those conditions. The radiators in the 124/126 OM603 diesels have a nasty tendency to plug internally such that they flow fine but do not transfer heat. A new radiator made my car go from constant 100-110C temps to refusing to budge over 95-100C. (Well, before my head replacement anyway, but that's a different story...)
Anyway, relax, your temps sound normal for being bloody hot outside...
HTH,