Choose a Light Color or a Light Fabric

• Whether an outfit is appropriate for an October wedding is not just about the color, but also about the fabric. To avoid looking like you're ready for spring, choose either a light color or a light fabric, but not both. For example, if you want to wear a light color, choose a heavier fabric.
  
  According to the book "Emily Post's Wedding Etiquette," appropriate autumn fabrics include: satin, brocade, taffeta, velvet, crepe and wool. For fall wedding colors, "Wedding Style" suggests orange, russet, green, purple and gold.
  
  

Consider The Climate and Time of Day

• Light colors are appropriate for October weddings that take place on sunny autumn afternoons and nuptials in warm climates. Feel free to pack your light colored formal wear to attend a destination wedding in Hawaii at any time of year. However, consider wearing a darker outfit for more formal evening weddings and in climates where October brings snow.
  
  

Help Create the Wedding's Ambiance

• A good guest adds to the ambiance of a wedding. The bride and groom planned an October wedding and picked out the venue to create a particular feel for their celebration. According to Clinton Kelly, of "What Not to Wear" fame, stylish guests follow the lead of their hosts by dressing appropriately for the wedding's atmosphere.
  
  If the invitation features autumn leaves, stick to a more traditional fall color.
  
  

Don't Upstage the Bride

• While it may seem a bit outdated, etiquette experts still agree that you shouldn't wear white to a wedding. Emily Post makes an exception only for men in hot climates. The reason for the 'no white rule' is still valid. You don't want to upstage the bride on her big day.
  
  These days, many brides are opting for off-white and tinted dresses. At an October wedding, your pastel yellow ensemble may look a lot like the bride's cream dress especially if all the other guests are wearing darker autumn colors. To avoid any faux pas when wearing light colored dresses, avoid dresses cut in the style of bridal gowns. Don't choose a light dress with a tight bodice and long full skirt. If you want to cover all your bases, ask a member of the wedding party what the bride is wearing, and steer clear of that hue.