EXTECH | Heat Stress WBGT (Wet Bulb Globe Temperature) Meter | HT200Specifications Range Max Resolution Basic Accuracy WBGT Wet Bulb Globe Temperature (w o sunlight) 32 to 138 F 0 to 59 C 0. 1 1. 8 F 1 C WBGT Wet Bulb Globe Temperature (w sunlight) 32 to 132 F 0 to 56 C 0. 1 2. 7 F 1. 5 C TG Black Globe Temperature 32 to 176 F 0 to 80 C 0. 1 1. 1 F 0. 6 C TA Air Temperature 32 to 122 oF 0 to 50 oC 0. 1 1. 5 F 0. 8 C Relative Humidity 1 to 99%RH 0. 1%RH 3%RH Dew Point 31. 5 to 120. 1 F 35. 3 to 48. 9 C 0. 1 Wet Bulb 6.