What is Stagnation Pressure?

Stagnation Pressure is the sum of the Velocity Pressure & Static Pressure. Stagnation temperature is the temperature of the fluid at the stagnation pressure and likewise static temperature is the temperature of the fluid at the static pressure.
 
The Stagnation temperature is the temperature that the fluid would reach if it were brought to a rest isentropically, converting its kinetic energy to enthalpy.