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Ready Marine Corps


Ready Marine Corps

Emergency Preparedness Program

Brought to You By Your Marine Corps Emergency Management Team
Flag Conditions
The Wet Bulb, Globe Temperature (WBGT) Index is the most effective means of assessing the effect of heat stress on the human body. The WBGT Index is used to determine Flag Conditions as a safety standard for how long individuals can safely work out of doors in hot humid conditions. Knowing and understanding these Flag Conditions will help keep you safe from heat-related emergencies like heat cramps, heat exhaustion, and heat/sun stroke. Color coded flags are flown in strategic locations on Marine Corps Installations to communicate hazardous conditions to personnel so that work and outdoor activity can be adjusted accordingly.
Color Definitions

 Flag Color

 WGBT Index (F)

 Intensity of Physical Exercise


80 – 84.9

Unacclimated personnel must perform heavy exercises with caution and under constant supervision. Organized PT evolutions in boots and utilities are allowed for all personnel.


85 – 87.9

Strenuous exercise and activity ( e.g., close order drill) should be curtailed for new and unacclimated personnel during the first 3 weeks of heat exposure.

 Red 88 – 89.9 

Strenuous exercise curtailed for all personne l with less then 12 weeks training in hot weather. Troops who are thoroughly acclimated may perform limited activity not to exceed 6 hours a day.

 Black 90 and Above 

Physical training and strenuous exercise suspended for all personnel (excludes operational commitment not for training purposes).

Note: Wearing of body armor or NBC uniform adds approximately 10 points to the measured WBGT index. Exposure limits should be adjusted accordingly.

  • Flag conditions are monitored from May 1 to Sept. 30, and any other day the temperature could hit 80 degrees.
  • There is one flag condition that’s determined by commanders, rather than the WBGT — “admin black.”

Set your own course through any hazard: stay informed, make a plan, build a kit.
Live Ready Marine Corps.

Where to Find Additional Information

Camp Lejeune Automated Heat Stress System— https://ahss.lejeune.usmc.mil/
Learn about conditions in Camp Lejeune’s mainside, Stone Bay, Courthouse Bay, Camp Geiger and Camp Johnson.

Marine Corps Base Butler and Marine Corps Air Station Futenma
Automated Heat Stress System: https://www.mccsokinawa.com/ahss/
The MCB Butler AHSS can also be accessed by download the MCCS Okinawa Liberty App under “Today”. 
Instructions for downloading the app to your device can be found at-- https://www.mccsokinawa.com/liberty/#tab0