In case of slow air flow there is enough time to warm up the air closer to the engine temperature. The faster the flow is, the closer is actual charge temperature to intake air temperature.
IAT = Intake Air Temperature
CLT = Coolant Temperature
Tcharge = CLT * (1 - Tcharge_coff) + IAT * Tcharge_coff

Inputs:

Tcharge_coff(rpm, TP)
Corner Case	Tcharge_coff
Rpm = 500/TP = 0%
Rpm = 8000/TP = 0%
Rpm = 500/TP = 100%
Rpm = 8000/TP = 100%

Rpm:
TP%:
Intake Air Temperature:
Coolant Temperature:

Result: