MAYPORT, Fla. – Naval Station Mayport said on Tuesday it was under “Black Flag” condition due to extreme heat.
But what does “Black Flag” condition mean?
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According to the official website of the U.S. Marine Corps, flag conditions are determined based on the Wet Bulb, Globe Temperature (WBGT) Index, which assesses the effect of heat stress on the human body.
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The WBGT Index is used to determine flag conditions as a safety standard for how long people can safely work outdoors in hot and humid conditions.
Here’s what each flag condition means:
| Flag Color | WGBT Index | Intensity of Physical Exercise |
|---|---|---|
| Green | 80-84.9°F | 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 | 85-87.9°F | Strenuous exercise and activity ( e.g., close order drill) should be curtailed for new and unacclimated personnel during the first three weeks of heat exposure. |
| Red | 88-89.9°F | Strenuous exercise curtailed for all personnel with less than 12 weeks of training in hot weather. Troops who are thoroughly acclimated may perform limited activity not to exceed six hours a day. |
| Black | 90°F and Above | Physical training and strenuous exercise suspended for all personnel (excludes operational commitment not for training purposes). |
Therefore, physical training and strenuous exercise at Naval Station Mayport were suspended for all personnel on Tuesday per the “Black Flag” condition alert.
Tuesday marks the fourth straight day of temperatures reaching 99 degrees or higher, a sizzling heat streak that’s drawing comparisons to some of the hottest stretches ever recorded in Northeast Florida.
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On Monday, Jacksonville peaked at 101, just short of the record-high 104. In Gainesville, however, a daily record was broken after temperatures hit 100 degrees, which topped the old record of 97, showcasing how the heat is stretching across north Florida.
An Extreme Heat Warning will remain in effect until 7 p.m. Tuesday.
With the heat index at dangerous levels, everyone is advised to take frequent breaks when outside, especially during peak heat.