Feels-like temperature: why does it differ from the thermometer?
The thermometer may show +3 °C while the forecast reports a feels-like temperature of −2 °C. Apparent temperature combines air temperature with factors such as wind and humidity to describe how conditions affect the human body.
The two main factors
1. Wind makes cold feel colder
A thin layer of warmed air forms next to the skin. Wind removes it, increasing heat loss; this is known as wind chill.
| Air temperature | Wind | Feels like |
|---|---|---|
| +5 °C | 20 km/h | about +1 °C |
| 0 °C | 30 km/h | about −6 °C |
| −5 °C | 40 km/h | about −14 °C |
2. Humidity makes heat feel hotter
Sweat cools the body by evaporating. In humid air evaporation slows down, so the body loses heat less effectively and hot weather feels more oppressive.
| Air temperature | Humidity | Feels like |
|---|---|---|
| 30 °C | 40% | about 29 °C |
| 30 °C | 70% | about 35 °C |
| 34 °C | 60% | about 41 °C |
Why it matters
- Clothing: on windy winter days, dress for wind chill.
- Exercise: reduce intensity and drink more in humid heat.
- Heat risk: apparent temperature often describes strain on the body better than air temperature alone.
- Frost: plants and objects cool to the actual air temperature; human wind chill does not apply to them.
Frequently asked questions
Why does my thermometer disagree?
Your thermometer measures air temperature. Feels-like temperature is calculated from several variables; they describe different things.
Does wind chill make pipes or plants colder than the air?
No. Wind can make them cool faster, but not below the actual air temperature.
When is apparent temperature dangerous?
In summer, values above about 40 °C can create a serious heat-illness risk. In winter, very low wind chill increases frostbite risk on exposed skin.