Below about 10°C, wind chill drives "feels like." Above about 27°C, humidity (heat index) does. In between, it’s just the thermometer.
Wind strips heat fastest when it’s already cold; humidity blocks sweat evaporation, which only matters once it’s hot. Neither effect does much in the mild middle.
Between about 10 °C and 27 °C neither index is defined, so a 'feels like' figure in that band is the plain temperature dressed up. Wind chill also assumes exposed skin and a walking pace — it says nothing about a cyclist at 30 km/h, and nothing at all in sunshine.
Estimate with the rule, then check it against the calculator that models it properly.
Open Feels Like Temperature →Below about 10°C, wind chill drives "feels like." Above about 27°C, humidity (heat index) does. In between, it’s just the thermometer. Wind strips heat fastest when it’s already cold; humidity blocks sweat evaporation, which only matters once it’s hot.