Wet Bulb Globe Temperature

Today's WBGT is shown at right.

The Wet Bulb Globe Temperature is a measure of heat stress in direct sunlight which takes into account the temperature, humidity, wind speed, sun angle and cloud cover (solar radiation).

Please view the current WBGT at right, and then use the WBGT and associated charts and other information on this page to aid in managing the work/rest cycles and fluid intake of personnel at Fort Belvoir.

Heat Category   1 Green, 2 Yellow, 3 Red, 4 Black, 5
WBGT Index, Degrees Farenheit   78 to 81.9  82 to 84.9 85 to 87.9 88 to 89.9 >90
 Easy Work  Work/Rest  NL  NL NL NL 50/10 minutes
 Easy Work   Water Intake (Qt/H)  1/2  1/2 3/4 3/4 1
 Moderate Work   Work/Rest  NL  50/10 minutes  40/20 minutes  30/30 minutes  20/40 minutes
 Moderate Work  Water Intake (Qt/H)  3/4  3/4  3/4  3/4  1
 Hard Work  Work/Rest  40/20 minutes  30/30 minutes  30/30 minutes  20/40 minutes  10/50 minutes
 Hard Work  Water Intake (Qt/H)  3/4  1 1 1 1

CAUTION: Hourly fluid intake should not exceed 1.5 quarts. Daily fluid intake should not exceed 12 quarts

  • The work-rest times and fluid replacement volumes will sustain performance and hydration for at least 4 hours of work in the specified heat category. Fluid needs can vary based on individual differences. (plus or minus .25 quart per hour) and exposure to full sun or full shade (plus or minus .25 quart per hour)
  • NL = No limit to work time per hour
  • Rest means minimal physical activity (sitting or standing), accomplished in shade if possible
  • Caution: Hourly fluid intake should not exceed 1.5 quarts
  • If wearing body armor add 5°F to WBGT in humid climates
  • If wearing NBC clothing (MOPP 4) add 10°F to WBGT

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

Last Updated 9/27/2019