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?
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.
RELATED | Extreme heat warning issued through tonight as brutal triple-digit heat index continues
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:
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.
RELATED | Jacksonville on pace to set record after four straight days of near-100-degree temperatures
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.
Copyright 2025 by WJXT News4JAX – All rights reserved.