Technical simple over-heating prob?

[secretmachine]

punto 60sx
1999

driving around, the temp needle sits around about halfway on the gauge, which would appear normal. however when sat in traffic the needle moves upto near the red zone.

if i'm sat stationary and rev the engine, holding it above the idling level, the temp needle will slowly go back down.

 

[custard]

when you rev the engine it moves the coolant around trhe engine allowing more cooling via the rad. now does the cooling fan come on when it hits the red?
if not you need to get this fixed ASAP
may be you have a worn water pump