5 Easy Ways to Extend Your Summer Wardrobe into Fall

"I'm attracted to very feminine clothes," says Vergara, who is appearing this month in the new 3-D film The Smurfs. This floral silk dress is perfect for an end-of-summer party, and it segues easily into fall with a chunky cardigan and high-heeled galoshes or a trench and stacked-heel boots. "These are fun outfits because they're so unexpected," Vergara says.

Floral silk dress, CH Carolina Herrera, $1,215; 212-744-2076. Chunky cardigan, Nanette Lepore, $448; 305-861-8212. High-heeled galoshes, Hunter Boot, $195; ShopBop.com. Trench, Burberry Brit, $750; Burberry.com. Stacked-heel Boots, Tommy Hilfiger, $498; 212-223-1824. Earrings, Irene Neuwirth, $7,770; Ylang23.com. Heels, Christian Dior, $1,100; 800-929-3467. Bracelet, Gabriele Frantzen, $280; StyleBop.com.

This airy cashmere-cotton pullover beautifully complements fall's floor-grazing skirt with a thigh-high slit. "Maxi lengths are so easy, and you look put-together," Vergara says. "I love pink—I want to live in this."

Pullover, Rebecca Taylor, $295; 212-243-2600. Skirt, Jenni Kayne, $695; ShopBop.com. Tank, Michael Michael Kors, $50; 866-709-5677. Earrings, Roni Blanshay for Jennifer Miller, $450; JenniferMillerJewelry.com. Bracelet, Marissa Klass, Muse Imports; 866-301-6873. Shoes, Edmundo Castillo, $635; EdmundoCastillo.com.

Teal is about to crop up everywhere, so pairing a wardrobe staple in the saturated shade—like a pencil skirt—with a statement piece like this short velvet motorcycle jacket makes for an easy closet update. "It's a showstopping color," Vergara says, "and the jacket is not something you would see everywhere."

Pencil skirt, L'Wren Scott, $1,275, Barneys; 888-822-7639. Motorcycle jacket, Callula Lillibelle, $525, Post 26, Santa Monica; 310-451-0950. Earrings, Alexis Bittar, $245; AlexisBittar.com. Ring, Nicholai by Nicky Hilton, $125, Joey Showroom, NYC; 212-675-8400.

The newly popular pleated skirt gets year-round wear with plain separates: Match it with layered tees now, a brightly colored cashmere cardigan come September. Traditional autumn shades—orange, bronze, gold—are also in style this summer.

Pleated skirt, Jill Stuart, $618; 212-343-2300. Cardigan, Mai Cashmere, $385; Mai-NYC.com. Small and large spear necklaces, Suzannah Wainhouse, $420 and $450, Love, Adorned, NYC; 212-431-5683. Brass and kyanite necklace, Suzannah Wainhouse, $480, Barneys New York; 888-822-7639. Three-ring necklace, Dannijo, $745; Dannijo.com. Shoes, Jimmy Choo, $795; JimmyChoo.com.

A snappy white tuxedo jacket takes a sheer tank top and cropped pants straight through winter. With its fitted cut and leather lapels, the jacket adds polish to jeans or leggings. A lacy metal clutch, sparkling bangle and cocktail ring have a similar smartening effect. Be on the lookout for Vergara's own line of clothing, accessories and footwear, debuting at Kmart in September. "A woman wants to feel beautiful, even when she's carpooling," Vergara says. "And style should be affordable—who wants to spend $500 on shoes?"

Tuxedo jacket, Tibi, $497; Tibi.com. Tank top, Bella Luxx, $38; 323-727-8060. Cropped pants, Ann Taylor, $88; AnnTaylor.com. Clutch, Bottega Veneta, $3,980; BottegaVeneta.com. Sparkling bangle, Atelier Swarovski by Mary Katrantzou, $407; AtelierSwarovski.com for stores. Cocktail ring, Suzanne Kalan, $3,480, Fragments, NYC; 212-334-9588.