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emergency-commsLast Reviewed: 2026-09-06
Emergency Alert & Warning Systems
Difficulty
beginner
Est. Time
30 minutes
Est. Cost
$0
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What has changed in this article
October 11, 2026
Corrected the county alert system: Contra Costa residents register with the Community Warning System (CWS), not AC Alert, which is Alameda County's system.
- Section 1 now describes the Community Warning System (cwsalerts.com) instead of AC Alert (Alameda County's system), and the checklist was rewritten for it.
- Added that Wireless Emergency Alerts need no registration, per the county.
- Removed claims about AC Alert (Alameda County's system) settings that we could not confirm for CWS.