County of Hawaii - Flood Awareness

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Know the Warnings

Not all floods are alike.

If it has been raining hard for several hours or steadily raining for several days, be alert to the possibility of a flood. 

Flash floods can happen quickly, sometimes in just a few minutes and without any visible signs of rain in your area. Flash floods often have a dangerous wall of roaring water that carries rocks, mud and other debris and can sweep away most things in its path. Be aware of streams, gulches, drainage channels, and other areas that appear harmless in dry weather. Flash floods can occur in these areas with or without such typical warnings as rain clouds or heavy rain.

Be alert to signs of flooding

  • If there is any possibility of a flash flood, move immediately to higher ground. Do not wait for instructions to move.
  • Real-time river gage data is available for the Waikoloa, Alakahi, Kawai Nui and Honoliʻi streams, Wailuku River, and Pāʻauʻau Gulch.
  • Listen for and respond to watches and warnings issued by the National Weather Service, the State Emergency Alert System (PDF) and the Hawaiʻi County Civil Defense Agency.
  • Civil Defense transmits warnings to the public through the Emergency Alert System's simultaneous broadcasts over all radio and television stations.
  • Sirens are activated to alert people to seek further information from the radio or TV stations.
  • Civil Defense operates a mass notification email and text messaging system. Use the link under "GET UPDATES" to register.

Know your flood watches and warnings

When a Flood Watch or Flash Flood Watch is issued

Flooding or a flash flood is possible.

Tune in to NOAA Weather Radio (KBA99 on 162.550 & 162.400 MHz or WWG27 on 162.550 MHz), the State Emergency Alert System or Hawaiʻi County Civil Defense messages on AM, FM or TV broadcast stations for information.

  • Be ready to act if a warning is issued or flooding occurs. Floods can happen quickly and without warning.
  • Review your flood preparedness plans and evacuation routes. If you live in a flood-prone area, be ready to evacuate at a moment’s notice and follow the instructions and advice of local officials.
  • Take steps to protect your home and your valuables.
  • Know how to safely shut off utilities.
  • Consider precautionary evacuation of your animals.