Automated Heat Stress System

The Automated Heat Stress System (AHSS) system is active from May 1st to Oct 31st. Please visit this page during this time frame for real-time AHSS updates.

Location WBGT Flag

Flag Condtions

The Wet Bulb, Globe Temperature (WBGT) Index is the most effective means of assessing the effect of heat stress on the human body. It does not reflect the ambient temperature, it reflects the heat stress condition that effects your 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. WBGT variations between each MCB Butler installation is normal and expected given the dynamic weather conditions here in Okinawa.

Color Defintions

Green, WBGT Index (°F): 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.

Yellow, WBGT Index (°F): 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, WBGT Index (°F): 88 – 89.9
Strenuous exercise curtailed for all personnel 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, WBGT Index (°F): 90 and Above
Physical training and strenuous exercise suspended for all personnel (excludes operational commitment not for training purposes).

Source: Ready Marine Corps - Emergency Prepardeness Program


For questions about the Heat Stress Flag Condition in your local area, please contact the appropriate office below:

Camp Foster, Camp Duty Officer, DSN: 645-7315 / Off-Base: 098-970-7315
Camp Kinser, Camp Services, DSN: 637-1886
Camp Hansen, Camp Services, DSN: 623-4649 / Off-Base: 098-969-4649
Camp Courtney, Camp Services, DSN: 622-9596 / Off-Base: 098-954-9596
Camp Schwab, Camp Services, DSN: 625-2215
MCAS Futenma, Station Weather, DSN: 636-3177
Camp Gonsalves (JWTC), DSN: 622-2238


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