The 2026 Cannes Film Festival has only just begun, but France's early-summer forecast is already testing VIP guests. Luckily, Demi Moore came prepared before the opening ceremony on May 12. Actually, the unruly breeze helped flaunt the 3D features on her custom polka-dot dress from Jacquemus . Demi Moore will be in full French Riviera fashion mode longer than most actors: She's joining Ruth Negga, Stellan Skarsgård, Chloé Zhao, and more film giants on the festival's jury. After posing with her fellow jurors, Moore gave Look 69 from Jacquemus's Fall 2026 collection the solo shots it deserved. Stylist Brad Goreski dressed The Substance star in a strapless, little white dress made for maximalists. Demi Moore was all smiles at the 2026 Cannes FIlm Festival in a polka-dotted Jacquemus dress. (Image credit: Getty Images) Primary colors—red, yellow, blue, and black—covered the belted bodice, billowy skirt, and peplum, ankle-grazing hem like perfectly-splattered paint.…