diff --git a/scripts/diagnose-calendar-timezone.js b/scripts/diagnose-calendar-timezone.js
new file mode 100755
index 0000000..baffbaa
--- /dev/null
+++ b/scripts/diagnose-calendar-timezone.js
@@ -0,0 +1,143 @@
+#!/usr/bin/env node
+
+// Diagnostic complet du décalage horaire Google Calendar
+const { Pool } = require('pg');
+
+const DATABASE_URL = process.env.DATABASE_URL;
+
+if (!DATABASE_URL) {
+  console.error('❌ DATABASE_URL non définie');
+  process.exit(1);
+}
+
+async function diagnose() {
+  const pool = new Pool({ connectionString: DATABASE_URL });
+
+  try {
+    console.log('\n═══════════════════════════════════════════════════════════');
+    console.log('🔍 DIAGNOSTIC DÉCALAGE HORAIRE GOOGLE CALENDAR');
+    console.log('═══════════════════════════════════════════════════════════\n');
+
+    const client = await pool.connect();
+
+    // 1. Timezone PostgreSQL
+    console.log('1️⃣  TIMEZONE POSTGRESQL:\n');
+    const tz = await client.query('SHOW timezone');
+    console.log(`   Server timezone: ${tz.rows[0].TimeZone}`);
+
+    const now = await client.query('SELECT NOW(), CURRENT_TIMESTAMP, CURRENT_TIMESTAMP AT TIME ZONE \'UTC\' as utc_now');
+    console.log(`   Server time: ${now.rows[0].now}`);
+    console.log(`   UTC time: ${now.rows[0].utc_now}`);
+
+    // 2. Colonnes calendar_events
+    console.log('\n2️⃣  COLONNES CALENDAR_EVENTS:\n');
+    const cols = await client.query(`
+      SELECT column_name, data_type, is_nullable
+      FROM information_schema.columns
+      WHERE table_name = 'calendar_events'
+        AND column_name IN ('start_time', 'end_time')
+      ORDER BY column_name
+    `);
+    cols.rows.forEach(row => {
+      console.log(`   ${row.column_name}: ${row.data_type} (nullable: ${row.is_nullable})`);
+    });
+
+    // 3. Exemple d'événements
+    console.log('\n3️⃣  EXEMPLE D\'ÉVÉNEMENTS (3 premiers):\n');
+    const events = await client.query(`
+      SELECT
+        id,
+        title,
+        start_time,
+        start_time AT TIME ZONE 'UTC' as start_time_utc,
+        start_time AT TIME ZONE 'Europe/Paris' as start_time_paris,
+        all_day
+      FROM calendar_events
+      ORDER BY start_time ASC
+      LIMIT 3
+    `);
+
+    if (events.rows.length === 0) {
+      console.log('   ⚠️  Aucun événement dans la base de données');
+      console.log('   → Synchronisez Google Calendar pour tester\n');
+    } else {
+      events.rows.forEach((evt, idx) => {
+        console.log(`   Événement ${idx + 1}: ${evt.title}`);
+        console.log(`     - start_time (brut): ${evt.start_time}`);
+        console.log(`     - start_time UTC: ${evt.start_time_utc}`);
+        console.log(`     - start_time Paris: ${evt.start_time_paris}`);
+        console.log(`     - all_day: ${evt.all_day}`);
+        console.log('');
+      });
+    }
+
+    // 4. Format renvoyé par le driver Node.js pg
+    console.log('4️⃣  FORMAT RENVOYÉ PAR LE DRIVER NODE.JS:\n');
+    if (events.rows.length > 0) {
+      const firstEvent = events.rows[0];
+      console.log(`   typeof start_time: ${typeof firstEvent.start_time}`);
+      console.log(`   start_time value: ${firstEvent.start_time}`);
+      console.log(`   start_time instanceof Date: ${firstEvent.start_time instanceof Date}`);
+
+      if (firstEvent.start_time instanceof Date) {
+        console.log(`   start_time.toISOString(): ${firstEvent.start_time.toISOString()}`);
+        console.log(`   start_time.toLocaleString('fr-FR'): ${firstEvent.start_time.toLocaleString('fr-FR', { timeZone: 'Europe/Paris' })}`);
+      }
+    }
+
+    // 5. Diagnostic du problème
+    console.log('\n5️⃣  DIAGNOSTIC:\n');
+
+    const hasBadData = await client.query(`
+      SELECT COUNT(*) as count
+      FROM calendar_events
+      WHERE synced_at < NOW() - INTERVAL '1 day'
+    `);
+
+    if (parseInt(hasBadData.rows[0].count) > 0) {
+      console.log(`   ⚠️  ${hasBadData.rows[0].count} événement(s) synchronisé(s) il y a plus d'1 jour`);
+      console.log('   → Ces événements peuvent avoir un mauvais timezone');
+      console.log('   → Recommandation: Supprimer et resynchroniser\n');
+    }
+
+    // 6. Vérifier si migration timezone a été appliquée
+    const migrationCheck = await client.query(`
+      SELECT data_type
+      FROM information_schema.columns
+      WHERE table_name = 'calendar_events'
+        AND column_name = 'start_time'
+    `);
+
+    const isTimestamptz = migrationCheck.rows[0].data_type.includes('timestamp with time zone');
+
+    if (!isTimestamptz) {
+      console.log('   ❌ PROBLÈME: Les colonnes sont encore en TIMESTAMP au lieu de TIMESTAMPTZ!');
+      console.log('   → La migration timezone n\'a pas été appliquée');
+      console.log('   → Lancez: node scripts/migrate-calendar-timezone.js\n');
+    } else {
+      console.log('   ✅ Les colonnes sont en TIMESTAMPTZ (correct)\n');
+    }
+
+    console.log('═══════════════════════════════════════════════════════════');
+    console.log('\n💡 SOLUTION RECOMMANDÉE:\n');
+    console.log('1. Supprimer tous les événements:');
+    console.log('   docker exec noteflow-postgres psql -U noteflow -d noteflow -p 5499 -c "DELETE FROM calendar_events"');
+    console.log('');
+    console.log('2. Resynchroniser Google Calendar depuis l\'interface web');
+    console.log('   Admin → Google Calendar → Bouton Synchroniser');
+    console.log('');
+    console.log('3. Vérifier que les heures correspondent maintenant');
+    console.log('');
+    console.log('═══════════════════════════════════════════════════════════\n');
+
+    client.release();
+    await pool.end();
+
+  } catch (error) {
+    console.error('\n❌ Erreur lors du diagnostic:', error.message);
+    console.error(error.stack);
+    process.exit(1);
+  }
+}
+
+diagnose();
diff --git a/scripts/migrate-calendar-timezone.js b/scripts/migrate-calendar-timezone.js
index 9f06518..a206fb5 100755
--- a/scripts/migrate-calendar-timezone.js
+++ b/scripts/migrate-calendar-timezone.js
@@ -58,7 +58,7 @@ async function migrate() {
     await client.query(`
       ALTER TABLE calendar_events
         ALTER COLUMN start_time TYPE TIMESTAMPTZ
-        USING start_time AT TIME ZONE 'UTC'
+        USING start_time AT TIME ZONE 'Europe/Paris'
     `);
     console.log('  ✅ start_time → TIMESTAMPTZ');
 
@@ -66,7 +66,7 @@ async function migrate() {
     await client.query(`
       ALTER TABLE calendar_events
         ALTER COLUMN end_time TYPE TIMESTAMPTZ
-        USING end_time AT TIME ZONE 'UTC'
+        USING end_time AT TIME ZONE 'Europe/Paris'
     `);
     console.log('  ✅ end_time → TIMESTAMPTZ');