T-Shirt or Pneumonia

What it does

One question: do I take a jacket. One answer: one enormous garment, from shorts to gloves, and a line from a mother who has been waiting all morning for you to walk out that door.

How it decides

The forecast comes from Apple Weather. What the app scores is not the temperature — it is what the air actually does to you.

Ten degrees in still sunshine is a t-shirt. Ten degrees with a thirty-kilometre wind is not. Wind chill and humidity are folded into a single perceived temperature, and the verdict is read off that, never off the thermometer.

Why six hours

You are not dressing for this minute. You are dressing for the next few hours, and you are not coming back for the coat. So the verdict is taken on the coldest point of the next six hours, not on your doorstep — and when that produces a coat while the sun is out, the app says why rather than looking broken.

What the glyph cannot say

A garment tells you how warm to dress and nothing else. So one line underneath names what it leaves out: rain, snow, a wind that gusts far above the steady wind, an evening about to turn colder, air heavy enough to notice.

What is in it

• A home screen widget that answers without opening anything, and without a network call of its own.
• Siri, for when your hands are full.
• The verdict read aloud, mutable in one tap.
• Eleven languages, each written on its own terms rather than translated. She compares you to the neighbour's kid in all of them.
• The last forecast received is kept on the phone, so the app still answers with no network.

What it does not do

It does not predict the weather: it reads a public forecast and scores it. It is not a medical service either — the name is a joke, and the app makes no health claim of any kind.

No account, no ads, no tracking, no notifications, no settings screen. If you decline location access, the app says so in its own voice rather than showing you an empty screen.