The thermometer is not wrong
Air temperature answers a narrow question: how warm or cold the air is. It does not describe how quickly sweat can evaporate on a humid afternoon, or how quickly wind carries heat away from exposed skin on a cold morning.
A feels-like value adds some of that missing context. The exact calculation can change by provider and by conditions, so there is no single formula that explains every feels-like number you see.
In hot weather, humidity changes the answer
The US National Weather Service uses heat index to describe how hot it feels when relative humidity is combined with air temperature. Its published heat-index values assume shade and light wind. Direct sunshine can make the experience hotter than that published number suggests.
That limitation matters. A shaded bus stop and an open playground can share the same forecast while giving you a different experience. Activity, clothing and access to water matter too.
In cold weather, wind carries heat away faster
Wind chill estimates the cooling effect of wind and cold on exposed skin. As wind increases, skin loses heat faster. The National Weather Service wind-chill guidance uses the index for cold conditions with enough wind for the calculation to apply.
Wind chill describes people and animals, not the final temperature of a parked car or a water pipe. Wind can make an object cool faster, but it cannot cool the object below the actual air temperature.
Use the number as context, not a verdict
Feels-like temperature is useful because it gets closer to the question you probably meant to ask: what will it be like when I step outside? It still does not know whether you will be running, sitting in shade, pushing a stroller or wearing a heavy coat.
Check the hours of your plan, then look at rain, wind, sun and humidity beside the feels-like value. FeelsLike puts that context on a 24-hour chart so one current reading does not make the whole decision for you.
Sources
- National Weather Service: Heat Forecast Tools
- National Weather Service: Wind Chill Chart
- National Weather Service: Mesoscale Analysis Definitions
Weather definitions and alert practices can vary by provider and country. Check your local weather authority for warnings and safety decisions.