The number your weather app calls "feels like" has never described you.
For most of a century it described a bottle. In 1940 Paul Siple and Charles Passel hung a small plastic cylinder of water from the roof of an Antarctic hut, level with the anemometer, and timed how long it took to freeze. What they published in 1945 was a cooling rate in kilocalories per square metre per hour — a four-digit number, not a temperature. Somebody else converted it into the friendly negative one a radio announcer could read.
That held until 2001, when a joint American, Canadian and British group replaced it. The current index models heat leaving a bare adult face turned into the wind, walking into it at 3.1 miles an hour. The wind comes off the standard anemometer at thirty-three feet and is scaled down to five feet, where a face is. The sky is clear and it is night, so the sun contributes nothing. Twelve volunteers, six men and six women, spent ninety minutes at a stretch on a treadmill in a chilled wind tunnel in Toronto with thermal transducers taped to their foreheads, cheeks, noses and chins.
The numbers came down hard. St. Louis reported 69 below on 20 January 1985; run that day through the current formula and it is 48 below.
None of which made the number about you. You have a hood up, you are standing still at a light, it is two in the afternoon and the sun is out. The old index at least sounded like an instrument. This one sounds like a person, and there is a particular one it means: bare-faced in the dark, walking into the wind at exactly 3.1 miles an hour.