Overview
IQAir now supports the heat index (also known as the felt temperature) across station and city widgets, as well as in the AirVisual real‑time API. The heat index integrates air temperature and relative humidity to indicate how hot conditions feel to the human body. Communicating the heat index alongside air quality, temperature, and humidity helps schools and communities make timely decisions about outdoor activities, heat stress precautions, and student well‑being.What is the Heat Index?
The heat index is a standardized metric used to estimate perceived heat stress by combining ambient temperature and relative humidity. When humidity is high, evaporative cooling from sweat is less effective, and conditions can feel significantly hotter than the measured air temperature. IQAir computes the heat index according to NOAA’s U.S. National Weather Service definition (see Heat Index Policy below).Station and city widgets
See our knowledge base article on how to create station or city widgets:
- The heat index can be configured to be displayed on station and city widget, additionally to the temperature or alternative to the temperature.
- You can choose whether to show them in degrees Celsius or Fahrenheit.
- The heat index field in the widget is color-coded to indicate the level of potential health impact. We are following the US convention of color coding as follows, in 5 levels from no health impact, caution, extreme caution, danger and extreme danger.
APIs
IQAir offers several APIs to access air quality data.- Air quality API:
- Find out more about IQAir’s air quality API on Access AirVisual's AQI, Air quality and pollution API | Knowledge Base | IQAir.
- Find out about the exact syntax in our API documentation here:
- Station API:
- Additionally, for contributors of IQAir AirVisual air quality monitoring stations (i.e. published outdoor air quality monitors), IQAir offers a so-called “station API”. Find more about it on How do I get my station's data through API? | Knowledge Base | IQAir.
- The heat index is available in all current and forecasting records in the API as an additional field “heatIndex” in degrees Celsius.
Heat Index Policy
We apply the heat index as defined by the U.S. National Weather Service (NOAA), using the formula published at Heat Index Equation.- Below ~26 °C (79 °F): The heat index is set equal to the temperature. This is because heat stress in this range is typically minimal, and NOAA’s heat index definition is not defined for cooler conditions.
- 26 °C–44 °C (79 °F–112 °F): We apply the full NOAA heat index formula, including adjustments for humidity, when conditions suggest heat stress may be present.
- Above 44 °C (112 °F): We continue to apply the formula even though it extends beyond the original validated range. This helps us account for extreme heat conditions that may still pose health risks.