| 0 | No Elevated Risk |
| 1 | Low Risk for those extremely sensitive to heat, especially those without effective cooling and/or adequate hydration |
| 2 | Moderate Risk for those who are sensitive to heat, especially those without effective cooling and/or adequate hydration |
| 3 | High Risk for much of the population, especially those who are heat sensitive and those without effective cooling and/or adequate hydration |
| 4 | Very High Risk for entire population due to long duration heat, with little to no relief overnight |