Heat Advisory: Issued when the Heat Index will be equal to or greater than 100°F, but less than 105°F.
Excessive Heat Warning: Heat indicies will attain or exceed 105°F.
Excessive Heat Watch: Possibility that Excessive Heat Warning Criteria may be met at longer ranges (12 to 48 hrs out).
For an outlook beyond 3-4 days, see the extended heat index guidance we get from the NWS's Hydrometeorological Prediction Center (HPC):
Maximum HEAT INDEX OUTLOOKS (for days 3-7) from the NWS Hydrometeorological Prediction Center (HPC) in DC.
All NWS State College Text Statements/Forecasts: