Temperatures in °F or °C: Automatic follows the household's country, or Settings says

README.md

@@ -22,6 +22,7 @@ copy holds that copy's secrets.
 - **Photos** from an iCloud shared album, straight from a phone, or from a folder.
 - **Text sized for the room.** Smaller, Standard or Larger, for the rows and the lists; the clock and the layout stay
   as they are.
+- **°F or °C** as the household's country uses, or as you choose in Settings.
 - **It behaves itself.** Brightness follows sunrise and sunset. After a while it drifts to photos and comes back. After a
   power cut, or with the internet down, it shows the last good screen and says from when.
 

dist/app.js

@@ -21,7 +21,7 @@
   var calProblem = false, tasksProblem = false;
   var page = 0, mode = 'calendar', themeChoice = 'auto';
   // Household preferences from the Settings view, stored on the server. These defaults are used until they load.
-  var PREFS = { rest: 'photos', restAfter: 5, mornings: 0, photoEvery: 60, appearance: 'auto', clock: 'auto', calendarView: 'week', textSize: 'standard' };
+  var PREFS = { rest: 'photos', restAfter: 5, mornings: 0, photoEvery: 60, appearance: 'auto', clock: 'auto', temperature: 'auto', calendarView: 'week', textSize: 'standard' };
   var prefs = withDefaults({});
   // What the server sends, over these defaults, so a setting it does not send yet still has its value.
   function withDefaults(data) { var out = {}, k; for (k in PREFS) out[k] = PREFS[k]; for (k in data) out[k] = data[k]; return out; }
@@ -87,6 +87,13 @@
     } catch (e) {}
     return (clockConvention[country] = uses24);
   }
+  // Fahrenheit or Celsius, as Settings says; on Automatic, as the household's country: Fahrenheit in the US and the few
+  // places that still use it, Celsius everywhere else. A household whose country is not known yet keeps the Fahrenheit
+  // it always had. The server always asks Open-Meteo in Fahrenheit, so its cache and the fixtures stay one thing.
+  var FAHRENHEIT = ['US', 'BS', 'BZ', 'KY', 'LR', 'PW', 'FM', 'MH'];
+  function celsius() { return prefs.temperature === 'C' || (prefs.temperature !== 'F' && /^[A-Z]{2}$/.test(household.country || '') && FAHRENHEIT.indexOf(household.country) < 0); }
+  // A temperature from the server, in °F, as a whole number in the unit shown. (+ 0 turns a rounded -0 into 0.)
+  function deg(f) { return Math.round(celsius() ? (f - 32) * 5 / 9 : f) + 0; }
   // "4 PM", "4:30 PM" or "16:00", "16:30": the 12-hour form drops :00 as people say it, the 24-hour form never does.
   function clockTime(d) { var h = d.getHours(), m = d.getMinutes(); return hours24() ? pad(h) + ':' + pad(m) : (h % 12 || 12) + (m ? ':' + pad(m) : '') + (h < 12 ? ' AM' : ' PM'); }
   // When something was last true, for a time that may be from another day: "5:39 PM" today, then "yesterday 5:39 PM",
@@ -346,13 +353,13 @@
     $('now').hidden = false;
     var t = now().getTime(), sun = sunTimes(now());
     drawIcon($('now-icon'), weather.code, t < sun.rise || t > sun.set);
-    $('now-temp').textContent = Math.round(weather.temperature) + '°';
+    $('now-temp').textContent = deg(weather.temperature) + '°';
     $('now-summary').textContent = describe(weather.code);
     // Apple's form: H and L first, then the one extra that matters today (rain, or a big feels-like gap). "H:104°" has
     // no space inside it to break at, so a label never wraps away from its number.
-    var feels = Math.round(weather.feelsLike), detail = 'H:' + Math.round(weather.high) + '° L:' + Math.round(weather.low) + '°';
+    var feels = deg(weather.feelsLike), detail = 'H:' + deg(weather.high) + '° L:' + deg(weather.low) + '°';
     if (weather.rain >= 20) detail += ' · ' + weather.rain + '% rain';
-    else if (Math.abs(feels - Math.round(weather.temperature)) >= 4) detail += ' · Feels like ' + feels + '°';
+    else if (Math.abs(feels - deg(weather.temperature)) >= (celsius() ? 2 : 4)) detail += ' · Feels like ' + feels + '°';
     $('now-detail').textContent = detail + (weather.stale ? ' · not updating' : '');
   }
   // A day's forecast in one short row: the icon, with the chance of rain under it where weather apps put it (so a wet day
@@ -364,8 +371,8 @@
     drawIcon(svg, fc.code); wx.appendChild(svg);
     if (fc.rain >= 30) wx.appendChild(node('small', '', fc.rain + '%'));
     row.appendChild(wx);
-    row.appendChild(node('b', '', Math.round(fc.high) + '°')); row.appendChild(node('span', '', Math.round(fc.low) + '°'));
-    row.setAttribute('aria-label', describe(fc.code) + ', high ' + Math.round(fc.high) + ', low ' + Math.round(fc.low) + (fc.rain >= 30 ? ', ' + fc.rain + ' percent chance of rain' : ''));
+    row.appendChild(node('b', '', deg(fc.high) + '°')); row.appendChild(node('span', '', deg(fc.low) + '°'));
+    row.setAttribute('aria-label', describe(fc.code) + ', high ' + deg(fc.high) + ', low ' + deg(fc.low) + (fc.rain >= 30 ? ', ' + fc.rain + ' percent chance of rain' : ''));
     return row;
   }
   function forecastFor(day) {
@@ -724,8 +731,8 @@
     if (!wx.hidden) {
       var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg'), rain = tomorrowSky.rain >= 30 ? ' · ' + tomorrowSky.rain + '% rain' : '';
       svg.setAttribute('class', 'wx-icon'); svg.setAttribute('viewBox', '0 0 64 64'); svg.setAttribute('aria-hidden', 'true'); drawIcon(svg, tomorrowSky.code);
-      wx.textContent = ''; wx.appendChild(svg); wx.appendChild(node('b', '', Math.round(tomorrowSky.high) + '°')); wx.appendChild(node('span', '', Math.round(tomorrowSky.low) + '°' + rain));
-      wx.setAttribute('aria-label', describe(tomorrowSky.code) + ', high ' + Math.round(tomorrowSky.high) + ', low ' + Math.round(tomorrowSky.low) + (rain ? ', ' + tomorrowSky.rain + ' percent chance of rain' : ''));
+      wx.textContent = ''; wx.appendChild(svg); wx.appendChild(node('b', '', deg(tomorrowSky.high) + '°')); wx.appendChild(node('span', '', deg(tomorrowSky.low) + '°' + rain));
+      wx.setAttribute('aria-label', describe(tomorrowSky.code) + ', high ' + deg(tomorrowSky.high) + ', low ' + deg(tomorrowSky.low) + (rain ? ', ' + tomorrowSky.rain + ' percent chance of rain' : ''));
     }
     var nodes = coming.map(function (item) {
       var el = itemNode(item, false);
@@ -1161,6 +1168,7 @@
     photoEvery: [[30, '30 sec'], [60, '1 min'], [120, '2 min'], [300, '5 min']],
     appearance: [['auto', 'Automatic'], ['light', 'Light'], ['dark', 'Dark']],
     clock: [['auto', 'Automatic'], ['12', '12-hour'], ['24', '24-hour']],
+    temperature: [['auto', 'Automatic'], ['F', '°F'], ['C', '°C']],
     calendarView: [['week', 'Week'], ['agenda', 'Agenda']],
     textSize: [['smaller', 'Smaller'], ['standard', 'Standard'], ['larger', 'Larger']],
     screen: [['auto', 'With the sun'], ['bright', 'Bright'], ['dim', 'Dim']]

dist/index.html

@@ -88,6 +88,7 @@ <h2 class="eyebrow">Photos</h2>
             <h2 class="eyebrow">Appearance</h2>
             <div class="setting"><p>Calendar</p><div class="choices" data-setting="calendarView"></div></div>
             <div class="setting"><p>Clock</p><div class="choices" data-setting="clock"></div></div>
+            <div class="setting"><p>Temperature</p><div class="choices" data-setting="temperature"></div></div>
             <div class="setting"><p>Text size</p><div class="choices" data-setting="textSize"></div></div>
             <div class="setting"><p>Theme</p><div class="choices" data-setting="appearance"></div></div>
             <div class="setting"><p>Brightness</p><div class="choices" data-setting="screen"></div></div>

settings.js

@@ -14,10 +14,11 @@ const OPTIONS = {
   appearance: ['auto', 'light', 'dark'], // auto follows sunrise and sunset where the household lives
   screen: ['auto', 'bright', 'dim'],     // backlight: with the sun, always bright, or always dim
   clock: ['auto', '12', '24'],           // auto is the convention of the household's country; 12-hour until that is known
+  temperature: ['auto', 'F', 'C'],       // auto is the household's country: Fahrenheit in the US and the few like it, Celsius elsewhere
   calendarView: ['week', 'agenda'],      // the days ahead as six columns, or as one list grouped by day
   textSize: ['smaller', 'standard', 'larger'] // what is read scales, rows with it; the glance layer and the layout do not
 };
-const DEFAULTS = {rest: 'photos', restAfter: 5, mornings: 0, photoEvery: 60, appearance: 'auto', screen: 'auto', clock: 'auto', calendarView: 'week', textSize: 'standard'};
+const DEFAULTS = {rest: 'photos', restAfter: 5, mornings: 0, photoEvery: 60, appearance: 'auto', screen: 'auto', clock: 'auto', temperature: 'auto', calendarView: 'week', textSize: 'standard'};
 
 function clean(input) {
   const out = {};

test/settings.test.js

@@ -54,6 +54,16 @@ test('Text size is a household setting: Standard unless chosen, one of three, ke
   assert.equal(settings.update({textSize: 'larger'}).textSize, 'larger');
 });
 
+test('Temperature is a household setting: Automatic unless chosen, °F or °C once chosen, kept across a restart', () => {
+  const file = tempFile(), settings = createSettings({file});
+  assert.equal(settings.read().temperature, 'auto');
+  assert.equal(settings.update({temperature: 'K'}).temperature, 'auto', 'only the three choices are accepted');
+  assert.equal(settings.update({temperature: 'c'}).temperature, 'auto', 'and exactly as written');
+  assert.equal(settings.update({temperature: 'C'}).temperature, 'C');
+  assert.equal(createSettings({file}).read().temperature, 'C', 'survives a restart');
+  assert.equal(settings.update({temperature: 'F'}).temperature, 'F');
+});
+
 // The play page (DESIGN.md → "A play page, for one household"): set only in the household's settings.json, never through
 // the API, and dropped unless it is a plain https address.
 const {cleanPlayPage} = require('../settings');

test/updates-server.test.js

@@ -127,10 +127,11 @@ test('A household’s data from 0.1.0 reads cleanly in this version', () => {
   assert.equal(settings.clock, DEFAULTS.clock, 'the new setting takes its default');
   assert.equal(settings.calendarView, 'week', 'and so does 0.1.2’s calendar view: the columns it always had');
   assert.equal(settings.textSize, 'standard', 'and 0.1.3’s text size: the size it always had');
+  assert.equal(settings.temperature, 'auto', 'and the temperature unit: Fahrenheit, as it always was, until a country is known');
   assert.equal(settings.rest, 'calendar'); assert.equal(settings.screen, 'dim'); assert.equal(settings.mornings, 8);
   // An older version reading what this one writes: it drops what it does not know and keeps the rest.
   const written = home.settings.update({clock: '24'});
-  const olderClean = input => Object.fromEntries(Object.entries(input).filter(([k]) => k !== 'clock' && k !== 'calendarView' && k !== 'textSize'));
+  const olderClean = input => Object.fromEntries(Object.entries(input).filter(([k]) => k !== 'clock' && k !== 'calendarView' && k !== 'textSize' && k !== 'temperature'));
   assert.deepEqual(olderClean(written), {rest: 'calendar', restAfter: 10, mornings: 8, photoEvery: 120, appearance: 'dark', screen: 'dim'});
   assert.equal(createSettings({file: path.join(dir, 'settings.json')}).read().clock, '24');
   fs.rmSync(data, {recursive: true, force: true});

test/wall.test.js

@@ -849,3 +849,21 @@ test('A monogram\'s letter takes the ink that reads on its person\'s colour, and
   assert.match(css, /\.forecast small,\.agenda-wx small\{[^}]*color:var\(--rain-ink\)/, 'the rain chance is text in --rain-ink');
   assert.match(css, /\.wx-icon \.drop\{stroke:var\(--rain\)\}/, 'the drops keep --rain');
 });
+
+test('Temperatures are in °F or °C as the household\'s country uses, or as Settings says', () => {
+  const house = country => ({'/api/household': {name: '', timezone: 'America/Chicago', place: 'Somewhere', ...(country ? {country} : {})}});
+  const settings = temperature => ({'/api/settings': {rest: 'calendar', restAfter: 5, mornings: 0, photoEvery: 60, appearance: 'auto', screen: 'auto', clock: 'auto', temperature}});
+  // The stress fixture is 101°F now, a high of 104°F and a low of 79°F, with an 80% chance of rain.
+  const shown = w => [w.$('now-temp').textContent, w.$('now-detail').textContent];
+  // An American household, and one whose country is not known yet, keep Fahrenheit.
+  for (const country of ['US', '']) assert.deepEqual(shown(load({now: '2026-09-23T10:00:00', overrides: house(country)})), ['101°', 'H:104° L:79° · 80% rain']);
+  // A British household, on Automatic, is in Celsius, and so is the week's forecast.
+  let w = load({now: '2026-09-23T10:00:00', overrides: house('GB')});
+  assert.deepEqual(shown(w), ['38°', 'H:40° L:26° · 80% rain']);
+  assert.ok(!/1\d\d°/.test(w.document.body.textContent), 'no Fahrenheit left anywhere on the wall');
+  // Settings overrides the country either way, and offers the three choices.
+  assert.equal(load({now: '2026-09-23T10:00:00', overrides: {...house('US'), ...settings('C')}}).$('now-temp').textContent, '38°');
+  assert.equal(load({now: '2026-09-23T10:00:00', overrides: {...house('GB'), ...settings('F')}}).$('now-temp').textContent, '101°');
+  const choices = w.document.querySelectorAll('[data-setting]').find(el => el.getAttribute('data-setting') === 'temperature');
+  assert.deepEqual(choices.children.map(b => b.textContent), ['Automatic', '°F', '°C']);
+});