Why are there two different temperatures in weather apps? Why don't we experience the real temperature instead of the 'Feels like'? How is 'Feels like' temperature measured?
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4$\begingroup$ The humidity affects the sensation of temperature because it affects the evaporation of sweat and the feels like value includes this. It may also include the effect of wind chill, though I think wind chill would usually be recorded separately. Whether this is a physics question is debatable. $\endgroup$John Rennie– John Rennie2025-12-29 09:18:46 +00:00Commented 2 days ago
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1$\begingroup$ As for the practical side of "perceiving temperature" by your body,- try to blow air to your hand in sauna and notice that at that skin place it feels "hotter". Similar effect in winter exists, strong winds amplifies heat convection from your skin, so it feels "colder". $\endgroup$Agnius Vasiliauskas– Agnius Vasiliauskas2025-12-29 13:07:40 +00:00Commented 2 days ago
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2$\begingroup$ Our biological bodies evolved not to measure environment temperature, but heat input/output power, since body must optimize inner engine (metabolism) to account for these factors. Our bodies are not in thermal equilibrium with environment, so measuring temperature has no of use in anycase. $\endgroup$Agnius Vasiliauskas– Agnius Vasiliauskas2025-12-29 13:19:54 +00:00Commented 2 days ago
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4$\begingroup$ There is physics in this question. Related - Why is a sleeping bag so cold when you first get in?. Not related, but still about the physics of perception - What is Gray, from a physics POV? $\endgroup$mmesser314– mmesser3142025-12-29 14:14:11 +00:00Commented 2 days ago
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7$\begingroup$ This is absolutely a physics question as the answer demonstrates. If it isn't then neither are questions about the appearance rainbows or why it hurts more when you fall from a higher height. This speaks to the same physics that explains why, when you go into a cold bathroom (where everything in it is the same temperature) that a porcelain sink feels colder to the touch than a towel. $\endgroup$JimmyJames– JimmyJames2025-12-29 21:54:02 +00:00Commented 2 days ago
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2 Answers
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Thermoception is a topic in psychophysics (or more broadly, in biophysics).
We generally perceive heat flux rather than temperature directly, as animal thermoceptors signal in response to skin temperature changes. However, heat flux (and hence skin temperature changes) depend on other physical factors than just air temperature. The heat flux is lower if the air is still and higher in wind (as the flow forcibly drives convection and disrupts an insulating boundary layer). The effectiveness of perspiration (to evaporatively dissipate waste metabolic heat from an animal's body) is reduced by ambient humidity, that is, by elevated wet bulb temperature. (These factors impact not just subjective sensation but also alter the survivability of extreme environments, for example wind chill affects rate of frostbite injury onset and wet bulb temperature predictions are important in placing an upper limit to human adaptability to climate change.)
In meteorology, a formula is used to account for these other physical factors that influence temperature perception, for example the Australian Bureau of Meteorology has used what is known as the Steadman Apparent Temperature:
$$T' = T_a + 0.33e - 0.70v - 4.00$$
Here, $T_a$ is the ambient air temperature (°C), $e$ is the atmospheric water vapour pressure (hPa), and $v$ is the near-surface wind speed (m/s). (The constant term represents how the body loses heat more easily than normal in air that is unusually dry.)
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2$\begingroup$ Everything in this answer is correct as written but it should also be noted that the thermal conductivity of air changes with temperature and humidity which also relates the effects already explained here. $\endgroup$JimmyJames– JimmyJames2025-12-29 21:45:38 +00:00Commented 2 days ago
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1$\begingroup$ According to this formula, on a hot day, wind would actually reduce the 'Feels like' temperature? $\endgroup$arjunsiva– arjunsiva2025-12-29 22:49:14 +00:00Commented 2 days ago
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4$\begingroup$ @arjunsiva yes. Table 3 of Steadman 1984 shows that a hot breeze can help cool (by assisting evaporation) unless the air is already extremely dry. Also note the model has a confined scope (such as excluding conditions above 54°C) and the linear formula is a simplification. $\endgroup$benjimin– benjimin2025-12-30 01:14:50 +00:00Commented 2 days ago
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$\begingroup$ Isn't that formula the one for Australian apparent temperature, rather than the one from Steadman's paper? $\endgroup$l0b0– l0b02025-12-30 07:55:32 +00:00Commented 2 days ago
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2$\begingroup$ @arjunsiva has your experience of breezy hot days and calm hot days been such that you would expect otherwise? What would you expect instead? Where have you experienced hot weather? Was it humid or dry? What was the temperature? $\endgroup$phoog– phoog2025-12-31 00:04:49 +00:00Commented yesterday
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Too long for a comment, hence posting an answer.
What we refer as “feels like temperature” is actually called Apparent temperature. It is the perceived temperature by humans which is caused by multiple factors like heat index, wind chill and overall globe temperature. It is invented by Robert G. Steadman (the equation is mentioned in benjimin’s answer).
Note that the actual temperature and the apparent temperature may not be equal and may deviate from the factors mentioned above (to the point where the apparent temperature becomes double of the actual temperature during windy subzero conditions). Here is a chart of the apparent temperature and how it deviates from actual temperature.
Based on Heat Index:
Based on Wind Chill:
Image source: https://www.popsci.com/environment/what-is-feels-like-temperature/
