diff --git a/src/lib/date-utils.ts b/src/lib/date-utils.ts
index f4fa324..ab8076e 100644
--- a/src/lib/date-utils.ts
+++ b/src/lib/date-utils.ts
@@ -19,3 +19,17 @@ export function getWeekYearLabel(date: Date = new Date()): string {
   const year = date.getFullYear();
   return `S${week.toString().padStart(2, '0')}-${year}`;
 }
+
+/** ISO week bounds (Monday 00:00:00 to Sunday 23:59:59.999) */
+export function getWeekBounds(date: Date): { start: Date; end: Date } {
+  const d = new Date(date);
+  const dayNum = d.getDay() || 7; // Sunday = 7
+  const diff = d.getDate() - dayNum + (dayNum === 7 ? -6 : 1); // Monday
+  const monday = new Date(d);
+  monday.setDate(diff);
+  monday.setHours(0, 0, 0, 0);
+  const sunday = new Date(monday);
+  sunday.setDate(monday.getDate() + 6);
+  sunday.setHours(23, 59, 59, 999);
+  return { start: monday, end: sunday };
+}
diff --git a/src/services/weather.ts b/src/services/weather.ts
index 72e10d4..a95e73a 100644
--- a/src/services/weather.ts
+++ b/src/services/weather.ts
@@ -1,5 +1,6 @@
 import { prisma } from '@/services/database';
 import { getTeamMemberIdsForAdminTeams } from '@/services/teams';
+import { getWeekBounds } from '@/lib/date-utils';
 import type { ShareRole } from '@prisma/client';
 
 // ============================================
@@ -301,21 +302,43 @@ export async function shareWeatherSessionToTeam(
     throw new Error('Session not found or not owned');
   }
 
-  // Get team members
+  // Max 1 météo par équipe par semaine
   const teamMembers = await prisma.teamMember.findMany({
+    where: { teamId },
+    select: { userId: true },
+  });
+  const teamMemberIds = teamMembers.map((tm) => tm.userId);
+  if (teamMemberIds.length > 0) {
+    const { start: weekStart, end: weekEnd } = getWeekBounds(session.date);
+    const existingCount = await prisma.weatherSession.count({
+      where: {
+        id: { not: sessionId },
+        date: { gte: weekStart, lte: weekEnd },
+        shares: {
+          some: { userId: { in: teamMemberIds } },
+        },
+      },
+    });
+    if (existingCount > 0) {
+      throw new Error("Cette équipe a déjà une météo pour cette semaine");
+    }
+  }
+
+  // Get team members (full)
+  const teamMembersFull = await prisma.teamMember.findMany({
     where: { teamId },
     include: {
       user: { select: { id: true, name: true, email: true } },
     },
   });
 
-  if (teamMembers.length === 0) {
+  if (teamMembersFull.length === 0) {
     throw new Error('Team has no members');
   }
 
   // Share with all team members (except owner)
   const shares = await Promise.all(
-    teamMembers
+    teamMembersFull
       .filter((tm) => tm.userId !== ownerId) // Don't share with yourself
       .map((tm) =>
         prisma.weatherSessionShare.upsert({