Table 2.

Apparent temperature thresholds and potential health impacts (after Steadman 1979)

Symptom Band	Classification Apparent	Temperature Range (°C)	Possible health effects on the body
I	Caution	27–32	Fatigue possible with prolonged exposure and/or physical activity
II	Extreme caution	33–39	Heat stroke, heat cramps, or heat exhaustion possible with prolonged exposure and/or physical activity
III	Danger	39–51	Heat cramps or heat exhaustion likely, and heat stroke possible with prolonged
IV	Extreme danger	> 51	Heat stroke highly likely