Table 2 Temperature-humidity index (THI) levels.
From: Assessing and forecasting collective urban heat exposure with smart city digital twins
Level | THI (℉) | Effect on the body |
|---|---|---|
Very warm |  > 80 | Prolonged exposure and activities may lead to fatigue, which may be severe enough to cause heat cramps. |
Hot |  > 90 | May lead to heat cramps and heat exhaustion, and in severe cases may lead to heat stroke. |
Very hot |  > 105 | The risk of heat cramps and heat exhaustion is very high, and heat stroke is probable in severe cases. |
Extremely hot |  > 128 | Heat stroke risk is high. |
