Summer dictates lighter, brighter colors and lightweight fabrics but that shouldn't be the only consideration.
Is the wedding formal? Is it being held in a church or temple? Is it an outdoor venue? What time of day is the ceremony? Is there a reception immediately following the ceremony, or will it be held hours later?
The invitation speaks volumes about what might be the most appropriate dress. A formally printed or engraved invitation on white or cream vellum or parchment with standard wording such as,
Mr. and Mrs. Jones request the honor of your presence . . ." dictates a more formal mode of dress.
Today, many couples are waiting longer to get married and are paying for the wedding themselves so they are in fact the hosts, rather than the brides parents which has been customary for many decades.
Dressing for an outdoor ceremony requires some thought. Where is the location? What will the weather be? A less formal mode of dress will probably be acceptable but the foremost consideration has to be comfort and appropriateness to the location. A black suit and high heel pumps will obviously look out of place at a beach wedding. A sundress would be a better choice but if the wedding is at sunset or later, you may be uncomfortably cool.
Formal ceremony held in a church or temple
A dress in your best basic or accent color, solid rather than printed, with understated jewelry and a simple pump. A dress with matching jacket could be the perfect choice. If the ceremony is after 4:00 pm, the jewelry can be more "glam."
Informal ceremony held in a church or temple
Skirt and blouse or pants and a blouse are good choices, but they should be quality fabrics and well-made, with whatever shoes and jewelry works well. A navy pant with a white or ivory silk blouse and a classic pump, worn with pearls or gold or silver chains is understated and not too formal, but still looks "classy."
Beachside, garden party or mountaintop venue
Dress for the location and the weather. A printed sleeveless dress for the beach or the garden is a good choice. A high-heeled sandal works well or a shoe with a flat or wedge heel if you will be walking on sand. Bring a sweater or shawl to wear once the sun goes down.
A mountaintop venue requires a slightly more rugged look so pants will likely work better than a dress. Solid pants worn with a sweater set is a good choice. A pair of flats, or perhaps boots, is a good shoe choice. A denim or leather jacket can be added if the weather turns colder.