1. If the WBGT device has been inside, allow at least 15 minutes for it to adjust to conditions when beginning measurement.
2. WBGT can change quickly in response to momentary fluctuations in wind and cloud cover; therefore, it is best to average readings over at least a 10 to 15 minute period.
3. If there is a marked change in weather/sky conditions during practice (e.g. skies clear, wind stops blowing), new WBGT measurements should be taken. Note that WBGT often increases rapidly during the mid-morning hours (as the sun rises in the sky) and decreases rapidly during the early evening hours (as the sun falls in the sky).
4. WBGT can vary greatly over different surfaces (e.g. grass field, artificial turf, tennis courts), so take your measurements at the same place as the outdoor activity.
5. WBGT should be measured 5 feet above the ground.