Massive US emergency alert test message to be sent in October. What to know.

In October, the mother of all emergency alerts will occur in the U.S., but don't be alarmed, it's only a test.

We're giving you a heads up, because it the test will be broadcast nationwide to your cell phone, TV, and radio. Here's what to know so you don't freak out and head to an underground bunker when it happens.

Where are these tests coming from and when?

The Federal Emergency Management Agency (FEMA) and the Federal Communications Commission (FCC) are planning a massive test of their Emergency Alert System (EAS) and Wireless Emergency Alerts (WEA) at approximately 2:20 p.m. ET. on October 4.

Why are FEMA and the FCC doing these tests?

The tests are being conducted in order to ensure that the testing systems works and does what it's supposed to do, which is send out a mass communication in the event of an actual emergency — not the false alarm in 2018 that briefly sent Hawaii into a state of panic, when inhabitants thought a ballistic missile was headed towards the islands.

What will the tests be exactly?

At that time, the WEA will send a message to your cell phone, and the EAS will send a message to your TV and radio. The message to your phone will happen within 30 minutes of the test, and will say in English or Spanish, "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed." So if you get that message, don't worry, it's not a scam. The alert will have a unique tone and vibration to ensure that people with disabilities will understand the message.

The message sent to TVs and radios will last for a minute and say, "This is a nationwide test of the Emergency Alert System, issued by the Federal Emergency Management Agency, covering the United States from 14:20 to 14:50 hours ET. This is only a test. No action is required by the public." This will sound like the other blaring, beeping tests you've heard before, so it should be somewhat familiar.

Do I need to do anything?

Nope. As the messages indicate, you don't need to do anything about it, just sit back and wait for it pass. Maybe set it on your calendar so you don't forget.