When a severe thunderstorm warning has been issued by the NWS predicting hazardous conditions such as large hail (1 ½ inches or greater based on storm history and trained spotter verification), destructive winds (70 mph or higher), or other hazards requiring immediate protective actions in order to save lives and property.
When a tornado warning has been issued by the National Weather Service (NWS) for Collin County naming McKinney in the path.
When a tornado has been sighted and confirmed in McKinney or is in close proximity to the city.
When a chemical spill / release presents public exposure and potential harm.
When a state or national emergency is declared by the governor or president.
When appropriate for other emergencies.
The first Saturday of each month at noon for testing, weather permitting.
The city has never used an all-clear as part of its warning process and will not sound the sirens to indicate an all-clear. By monitoring the situation, you can make informed decisions and know when it is safe to leave your designated safe room.