Climate change brings increasing urgency to understanding wet bulb temperature - a crucial measurement combining heat, humidity, sun exposure, and wind factors. Unlike the heat index, which measures perceived temperature in shade, wet bulb temperature accurately reflects how heat affects the body during outdoor activities. Once it exceeds 90 degrees, safety guidelines recommend limiting outdoor work to just 15 minutes per hour - critical knowledge as we experience an additional 41 days of dangerous heat annually due to climate change.