diff --git a/app.js b/app.js
index 62123470..9ddd307a 100644
--- a/app.js
+++ b/app.js
@@ -44,7 +44,7 @@ app.set('view engine', 'jade');
 app.use(logger('dev'));
 app.use(cookieParser());
 app.use(cachify);
-app.use((req, res, next) => {
+app.use((_req, res, next) => {
   cachify.helpers().then(fns => {
     res.locals.cachify = fns.cachify;
     next();
diff --git a/biome.json b/biome.json
index 4618d9ed..da8fbb90 100644
--- a/biome.json
+++ b/biome.json
@@ -30,6 +30,9 @@
     "enabled": true,
     "rules": {
       "recommended": true,
+      "correctness": {
+        "all": true
+      },
       "complexity": {
         "noForEach": "off",
         "useLiteralKeys": "off"
@@ -44,5 +47,24 @@
         "noAssignInExpressions": "off"
       }
     }
-  }
+  },
+  "overrides": [
+    {
+      "include": [
+        "**/sw.template.js"
+      ],
+      "linter": {
+        "rules": {
+          "correctness": {
+            "noUndeclaredVariables": "off"
+          }
+        }
+      },
+      "javascript": {
+        "globals": [
+          "options"
+        ]
+      }
+    }
+  ]
 }
diff --git a/lib/cli/fetch.js b/lib/cli/fetch.js
index 67780bf2..35603b2f 100644
--- a/lib/cli/fetch.js
+++ b/lib/cli/fetch.js
@@ -10,7 +10,7 @@ function fetchExample(resortId) {
     resort = require(`../resorts/${resortId}/resort.json`);
     curl(resort.dataUrl || resort.api || resort.url, resortId);
     done = true;
-  } catch (e) {
+  } catch {
     console.error(resortId, 'is not a valid resort ID');
     process.exit(1);
   }
diff --git a/lib/cli/generate.js b/lib/cli/generate.js
index 28f7778d..7a852404 100644
--- a/lib/cli/generate.js
+++ b/lib/cli/generate.js
@@ -114,7 +114,7 @@ function write(dst, json) {
 
 function copy(src, dst, params) {
   console.log('Generating %s...', dst);
-  fs.readFile(src, 'utf8', (err, data) => {
+  fs.readFile(src, 'utf8', (_err, data) => {
     data = template(data)(params);
     fs.writeFileSync(dst, data);
   });
diff --git a/lib/cli/noaa.js b/lib/cli/noaa.js
index cd5cab0f..bb439f3a 100644
--- a/lib/cli/noaa.js
+++ b/lib/cli/noaa.js
@@ -61,7 +61,7 @@ function writeDescriptor(resortId, descriptor) {
 function readDescriptor(resortId) {
   try {
     return require(`../resorts/${resortId}/resort.json`);
-  } catch (e) {
+  } catch {
     console.error(resortId, 'is not a valid resort ID');
     process.exit(1);
   }
diff --git a/lib/lifts/index.js b/lib/lifts/index.js
index b1d39f1e..49bb9c11 100644
--- a/lib/lifts/index.js
+++ b/lib/lifts/index.js
@@ -48,7 +48,7 @@ function fetch(resort, fn) {
   }
   debug("Fetch lift status for %s", resort.id);
   const rfau = resort._rfau;
-  rfau.fn(rfau.url, resort._parseFn, (err, data) => {
+  rfau.fn(rfau.url, resort._parseFn, (_err, data) => {
     Promise.resolve(data).then((data, err) => {
       if (err || !data) {
         data = {};
diff --git a/lib/loaders.js b/lib/loaders.js
index fe281c94..500d7e99 100644
--- a/lib/loaders.js
+++ b/lib/loaders.js
@@ -23,7 +23,7 @@ function appendResorts(data, resorts) {
 
 function load(fn) {
   debug('Loading resorts...');
-  async.parallel(loaders, (err, results) => {
+  async.parallel(loaders, (_err, results) => {
     const data = results.reduce(appendResorts, Object.create(null));
     debug('Loaded %d resorts.', Object.keys(data).length);
     fn(null, data);
diff --git a/lib/routes/data.js b/lib/routes/data.js
index 9eb84f6e..368cabe8 100644
--- a/lib/routes/data.js
+++ b/lib/routes/data.js
@@ -155,7 +155,7 @@ function data() {
 
   function init(fn) {
     // all loaders
-    loaders.load((err, data) => {
+    loaders.load((_err, data) => {
       initCache(data);
       my.tags = tags(data);
       my.all = Object.keys(cache);
diff --git a/lib/routes/headers.js b/lib/routes/headers.js
index 7868c60d..8722dc12 100644
--- a/lib/routes/headers.js
+++ b/lib/routes/headers.js
@@ -34,7 +34,7 @@ const reportTo = JSON.stringify({
   ]
 });
 
-function csp(req, res, next) {
+function csp(_req, res, next) {
   const cspNonce = crypto.randomBytes(16).toString('base64');
   res.locals.cspNonce = cspNonce;
   res.header(CSP_HEADER_NAME, cspPolicy.replace('$random', cspNonce));
@@ -44,18 +44,18 @@ function csp(req, res, next) {
   next();
 }
 
-function referrer(req, res, next) {
+function referrer(_req, res, next) {
   res.header('Referrer-Policy', 'no-referrer-when-downgrade');
   next();
 }
 
-function feature(req, res, next) {
+function feature(_req, res, next) {
   res.header('Feature-Policy', `fullscreen 'self'`);
   next();
 }
 
 
-function link(req, res, next) {
+function link(_req, res, next) {
   const preloadLinks = [{
       path: '/stylesheets/fonts/lift-status.woff2',
       as: 'font',
diff --git a/lib/routes/index.js b/lib/routes/index.js
index 8303152c..a2581d51 100644
--- a/lib/routes/index.js
+++ b/lib/routes/index.js
@@ -50,7 +50,7 @@ function renderResorts(req, res, next) {
  *   /resort/<name> - display a specific resort
  *   /?resorts=<name1>,<name2>... - display resorts on the list
  */
-function index(req, res, next) {
+function index(req, _res, next) {
   req.requested = req.params.resort || req.query.resorts;
   req.opts = {
     openSingle: true
@@ -92,7 +92,7 @@ function tag(req, res, next) {
   next();
 }
 
-function about(req, res) {
+function about(_req, res) {
   res.render('about', {
     title: title('About')
   });
@@ -162,7 +162,7 @@ function meta(req, res, next) {
 
 function routes(app) {
 
-  function reqData(req, res, next) {
+  function reqData(req, _res, next) {
     req.data = app.data;
     next();
   }
diff --git a/lib/routes/service-worker.js b/lib/routes/service-worker.js
index 78c11469..14b8a06a 100644
--- a/lib/routes/service-worker.js
+++ b/lib/routes/service-worker.js
@@ -11,7 +11,7 @@ const {
 
 const DEBUG = NODE_ENV !== 'production';
 
-function renderServiceWorker(req, res) {
+function renderServiceWorker(_req, res) {
   createServiceWorkerScript(res.locals).then(serviceWorkerScript => {
     // do not cache service worker
     res.header('Cache-Control', 'no-cache, max-age=0, must-revalidate');
diff --git a/test/lifts/index.js b/test/lifts/index.js
index 91ddef97..cf27db34 100644
--- a/test/lifts/index.js
+++ b/test/lifts/index.js
@@ -13,7 +13,7 @@ function testResort(name, ext, expected, opts = {}) {
   const parse = makeParse(name);
 
 
-  function testHTML(t, done) {
+  function testHTML(_t, done) {
     const stream = createReadStream(filename);
 
     stream.on('error', done);
@@ -24,7 +24,7 @@ function testResort(name, ext, expected, opts = {}) {
     }));
   }
 
-  function testJSON(t, done) {
+  function testJSON(_t, done) {
     const asyncParse = parse.isAsync ?
       parse :
       (data, fn) => process.nextTick(fn, null, parse(data));
diff --git a/test/opening.js b/test/opening.js
index 9c29efa7..875bff15 100644
--- a/test/opening.js
+++ b/test/opening.js
@@ -14,14 +14,14 @@ const today = iso(now);
 const future = iso(now + 2 * day);
 const past = iso(now - 2 * day);
 
-test('opening should be empty for missing dates', (t, done) => {
+test('opening should be empty for missing dates', (_t, done) => {
   opening({}, (err, od) => {
     assert.ok(!od);
     done(err);
   });
 });
 
-test('opening should be empty for invalid dates', (t, done) => {
+test('opening should be empty for invalid dates', (_t, done) => {
   opening({
     opening: 'abc'
   }, (err, od) => {
@@ -30,7 +30,7 @@ test('opening should be empty for invalid dates', (t, done) => {
   });
 });
 
-test('opening should be empty for past dates', (t, done) => {
+test('opening should be empty for past dates', (_t, done) => {
   opening({
     opening: past
   }, (err, od) => {
@@ -39,7 +39,7 @@ test('opening should be empty for past dates', (t, done) => {
   });
 });
 
-test('opening should be empty for today', (t, done) => {
+test('opening should be empty for today', (_t, done) => {
   opening({
     opening: today
   }, (err, od) => {
@@ -48,7 +48,7 @@ test('opening should be empty for today', (t, done) => {
   });
 });
 
-test('opening should be present for future dates', (t, done) => {
+test('opening should be present for future dates', (_t, done) => {
   opening({
     opening: future
   }, (err, od) => {
diff --git a/test/weather/noaa.js b/test/weather/noaa.js
index 3877977c..dce39dda 100644
--- a/test/weather/noaa.js
+++ b/test/weather/noaa.js
@@ -4,7 +4,7 @@ const noaa = require('../../lib/weather/noaa');
 
 require('../replay');
 
-test('noaa should return empty forecast if location is missing', (t, done) => {
+test('noaa should return empty forecast if location is missing', (_t, done) => {
   noaa({
     ll: [0, 0]
   }, (err, forecast) => {
@@ -14,7 +14,7 @@ test('noaa should return empty forecast if location is missing', (t, done) => {
   });
 });
 
-test('noaa should return forecast for valid location', (t, done) => {
+test('noaa should return forecast for valid location', (_t, done) => {
   noaa({
     // Killington, VT
     noaa: 'BTV/107,21',
diff --git a/test/weather/openweather.js b/test/weather/openweather.js
index 39b531bd..b921ab97 100644
--- a/test/weather/openweather.js
+++ b/test/weather/openweather.js
@@ -4,7 +4,7 @@ const openweather = require('../../lib/weather/openweather');
 
 require('../replay');
 
-test('openweather should return forecast', (t, done) => {
+test('openweather should return forecast', (_t, done) => {
   openweather({
     // Killington, VT
     ll: [-72.7933, 43.6647]
diff --git a/test/webcams.js b/test/webcams.js
index 87cc19e5..5be76f3c 100644
--- a/test/webcams.js
+++ b/test/webcams.js
@@ -8,7 +8,7 @@ if (process.env.REPLAY !== 'record') {
   process.env.WEBCAMS_API_KEY = 'TEST_KEY';
 }
 
-test('webcams should return no webcams if location is missing', (t, done) => {
+test('webcams should return no webcams if location is missing', (_t, done) => {
   webcams({}, (err, webcams) => {
     assert.ifError(err);
     assert.ok(!webcams);
@@ -16,7 +16,7 @@ test('webcams should return no webcams if location is missing', (t, done) => {
   });
 });
 
-test('webcams should return webcams for valid location', (t, done) => {
+test('webcams should return webcams for valid location', (_t, done) => {
   webcams({
     counter: 1,
     ll: [7.98, 46.54] // from API examples https://windy.com/webcams/1697038975'