A combined "apparent" temperature that accounts for humidity (in heat) or wind (in cold), reflecting how hot or cold the air really feels on your skin.
measurementWhat is Feels-Like Temperature?
The feels-like temperature — also called “apparent temperature” — is a single combined number that captures how the air actually feels to a human body, accounting for temperature plus other factors:
- In hot weather (above ~27°C): adds the effect of humidity via the heat index formula. Humid air feels much hotter than the thermometer shows.
- In cold weather (below ~10°C): adds the effect of wind via the wind chill formula. Windy air strips heat from skin and feels much colder.
This concept matters because the human body senses heat and cold differently than a thermometer does. A thermometer reads only air temperature. Your body experiences a complex interaction between air temperature, your sweat rate, evaporation rate, wind, and direct sun exposure.
For South Asian residents during summer monsoon, feels-like is arguably the most important weather number — often 6–10°C higher than the air temperature, pushing days routinely into dangerous heat territory.
Why feels-like matters more than air temperature
Three reasons:
- Humidity blocks sweating — Sweat cools you by evaporating. In 85% humidity, sweat doesn’t evaporate efficiently; your body cooling fails even at “moderate” 35°C air temperature.
- Wind speeds heat loss — Cold wind strips warmth from skin much faster than still cold air. A windy 5°C feels colder than a calm −5°C.
- Sun adds 8–10°C — Even after accounting for humidity, direct sun adds significant heat exposure not captured in the standard formula.
A common error: dismissing humid heat because “it’s only 34°C.” That same 34°C with 80% humidity has a feels-like of 45°C — well past the danger threshold for prolonged outdoor activity.
How feels-like is calculated
There are two formulas, used depending on the temperature range:
Heat Index (hot weather): The US National Weather Service formula combines temperature and relative humidity:
HI = a + b·T + c·RH + d·T·RH + e·T² + f·RH² + g·T²·RH + h·T·RH² + i·T²·RH²(Where T = temperature in °F, RH = relative humidity %, and a-i are regression coefficients.)
Valid only when T ≥ 27°C and RH ≥ 40%.
Wind Chill (cold weather): The North American formula combines temperature and wind speed:
WC = 13.12 + 0.6215·T − 11.37·V^0.16 + 0.3965·T·V^0.16(Where T = temperature in °C, V = wind speed in km/h.)
Valid only when T ≤ 10°C and V ≥ 5 km/h.
Combined apparent temperature: Many weather services (including most apps) use a hybrid: heat index in summer, wind chill in winter, with a smooth blending zone.
The Mausam Online and Open-Meteo “feels-like” temperature follows this combined approach.
Feels-like in South Asia
The contrast across South Asian climates is striking:
Coastal cities during monsoon (May–September):
- Mumbai: 32°C actual → 42°C feels-like (10°C gap)
- Chennai: 33°C actual → 43°C feels-like
- Karachi: 35°C actual → 45°C feels-like (peak summer)
- Dhaka: 34°C actual → 44°C feels-like
- Kolkata: 34°C actual → 42°C feels-like
Inland dry cities during summer (April–May):
- Delhi (peak May): 44°C actual → 46°C feels-like (small gap)
- Jaipur: 45°C actual → 47°C feels-like
- Bikaner: 47°C actual → 48°C feels-like
- Sukkur (Pakistan): 47°C actual → 49°C feels-like
The “small gap” in dry inland cities is because RH is often below 30%, so the heat-index formula adds little. The “large gap” in coastal cities is because RH 70-85% disrupts evaporative cooling.
When does feels-like become dangerous?
Health-risk thresholds:
| Feels-like | Risk |
|---|---|
| Below 27°C | Comfortable for most |
| 27–32°C | Caution; fatigue with prolonged exertion |
| 32–41°C | Extreme caution; cramps, exhaustion |
| 41–54°C | Danger; heat stroke possible |
| Above 54°C | Extreme danger; heat stroke imminent |
For coastal South Asian cities during peak summer/monsoon, feels-like routinely exceeds 45°C for hours at a time — placing the entire population in the “Danger” zone. Outdoor workers, the elderly, children and people without AC are at very high risk.
Feels-like vs wet-bulb temperature
These two metrics are closely related but distinct:
- Feels-like (heat index) is a US NWS engineering formula. Used for public warnings.
- Wet-bulb temperature is a physical measurement — the lowest temperature you can reach via evaporative cooling. Used by climate scientists.
- Wet-bulb 35°C is considered the human survivability limit.
Roughly, feels-like 54°C corresponds to wet-bulb ~32°C, which corresponds to about the upper limit for safe outdoor exertion. Wet-bulb 35°C means even healthy adults face heat-stroke risk within hours.
Feels-like on Mausam Online
Mausam Online displays feels-like temperature alongside actual temperature on every city page. The values come from Open-Meteo’s “apparent temperature” calculation, which combines:
- Surface air temperature
- Relative humidity
- Wind speed
- Solar radiation
This integrated value is more representative of body heat stress than air temperature alone.
Frequently asked questions
Why is humid heat more dangerous than dry heat? Your body cools through sweat evaporation. High humidity slows or prevents evaporation. Your body temperature rises even when the thermometer doesn’t. At 35°C with 85% humidity, the body cannot dissipate metabolic heat — leading to heat stroke within hours.
Is “feels-like” the same as wet-bulb temperature? Not exactly. Feels-like (heat index) is a regression formula calibrated to perceived heat. Wet-bulb is a physical measurement of evaporative cooling potential. Wet-bulb 35°C ≈ feels-like 50-55°C ≈ heat stroke risk for healthy adults.
Why does Mumbai feel hotter than Delhi at the same temperature? Humidity. Mumbai in May has 70-80% RH; Delhi has 20-30%. At 35°C: Mumbai feels-like is ~42°C, Delhi feels-like is ~36°C. The 5-7°C gap reflects the difference in sweat evaporation efficiency.
Does feels-like account for sun? Standard heat-index formulas assume shade. Direct sun adds 8–10°C to perceived heat. The Open-Meteo “apparent temperature” includes solar radiation, so its value is closer to what you’d feel in actual outdoor conditions.
Where can I see live feels-like for my city? Mausam Online displays feels-like temperature on every city page. See Mumbai, Chennai, Karachi, Dhaka, Kolkata, Delhi, Bengaluru.