You may not have heard about CMAS yet. I didn’t know about it until my wife’s new Verizon phone started giving us very loud weather alerts. They even happened in the middle of the night and were very annoying.
Your cell phone may be a little different but this is how I turned off the alarms. Navigate to: Messages - More - Settings - Emergency Alerts. If you can’t find the proper menu you can call 611 on your cell phone which will connect you to your carrier.
Upon further research on the Internet and found an explanation of CMAS. Congress has passed a law that allows the President to issue alerts and other alerts can be issued regarding imminent threats to safety or life, and Amber alerts.
You can turn off the last two but not messages from the President. As of this writing these alerts do not apply to the iPhone.
You can read all about this on the Government Web Site.