Ok so you're running into some ambiguous dress codes here. Cocktail USED to mean evening wear one step below a tuxedo (dark, simple suits.) Like you were going to after-dinner cocktails. In recent years it has come to mean "less formal, light colors acceptable, but still be dressed up." You could wear a sport coat to the current iteration of "cocktail" and be ok but I would ask the host. Summer formal doesn't really mean anything. Formal means white tie or morning dress depending on time of day. It's extremely unlikely that this is what they expect. I'm assuming what they mean is that light colored and non-wool suits are acceptable. Again, I would ask them. More on reddit.com

You should definitely wear a jacket/blazer. It's a sign of respect to the people getting married. More on reddit.com

How to properly interpret the ambiguous dress code? These days people don't abide by the traditional phrasing of formal events. It used to be that: Formal = White Tie, Semi-Formal = Black Tie, Informal = Suits. As casual has become the norm and formal events have become rarities this nomenclature is no longer held to such strict standards. Nowadays: formal = suits, semi-formal = business casual, informal = casual. If this wording is seen on your invitations, make sure you've properly interpreted the meaning. Invitations may not explicitly state the dress code. Oftentimes they'll use buzz-words and adjectives to describe how to dress. Your task is assigning their made-up dress code into an easily digestible set of guidelines. The following list is from most to least formal and should encompass nearly any wedding's dress code. Try to categorize the wedding you're attending onto this list to give you a basic starting point of wardrobe options. Black Tie Required - Tuxedos are required, if you don't own one, rent. Black Tie Optional - Try your hardest to rent, borrow, or buy a tuxedo. If all else fails, a dark (read: black, midnight, or charcoal) suit with black neck-wear and black shoes is acceptable. Suit Required - Wear a suit with a tie. If you don't own one: buy, rent, or borrow one. Jacket / Tie Optional - Wear a suit if you can, wear a blazer and tie as the second option. A sweater/cardigan with a tie (weather permitting) is next. Try your hardest NOT to wear a dress shirt and tie WITHOUT a jacket. Leather dress shoes are a must. Cocktail Attire - A more formal and celebratory business casual. Jacket and ties may be required. A suit may be considered. Leather dress shoes required. Business Casual - The entire range of business casual is allowed. Try to stay on the more formal side of things with a sport coat and tie. You can go as casual as khaki chinos, an OCBD, and boat shoes. No sneakers, no jeans. On the flip side, you don't want to be the only attendee wearing a a full suit. Country Casual - Jackets aren't recommended, but if you must, wear linen, tweed, or another casual fabric. Chinos, a button-up, and casual leather shoes are recommended. Jeans and more casual shirts (read: plaids or chambray) are acceptable. Shirt should have a collar. Preferably, no sneakers. California Casual - Anything goes really. Shorts, tee shirts, and sneakers are all acceptable. I'd still recommend something respectable for the occasion such as chinos, a button-up shirt, and some casual leather shoes. Feel free to wear something much more akin to your personal style though. Beach Casual - Vacation wear is recommended. Linen pants, floral shirts, and sandals are all good options. If you're unsure about the formality of a casual wedding dress-code, err on the side of business casual and bring a jacket and tie, you can always remove them if you feel over-dressed. A note on matching your date. You DO NOT need to color-coordinate EXACTLY with your date. It would be nice if you complimented each other. It would be smart not to clash. There's nothing stipulating that you Hhave to match though. This isn't your high-school prom. If your S.O. is a part of the wedding party you need to worry even less about matching considering their outfit was chosen by the bride/groom. If YOU are in the wedding party and the Bride or Groom hasn't told you what you should wear, please reach out to them and ask. A note on asking for help on r/mfa concerning wedding attire. It's nigh impossible to properly describe every scenario one might encounter for a wedding, so asking for advice is always a good idea. I would like to recommend that if you're going to ask r/mfa , please provide the following: Adequate details of the wedding: time, date, location, formality/dress code (if known) Photos of your clothing or examples of clothing you've considered thus far A BUDGET you're trying to work within And please give yourself more than a week to get stuff done. This will help MFA members give more sound advice and it'll show that you've put forth some effort as well. Thanks, -dav p.s. This isn't a buyer's guide because, IMO, you shouldn't have to buy new clothing every time a wedding comes up. This is a guide to figure out what's in your wardrobe that will look great. If you're looking for some places to buy some suits/shirts/ties, read the sidebar, particularly: Guide to Weddings MTM Shirts Overly Long List of Resources Put This On's guide for wedding guests PTO's guide to summer weddings A Suitable Wardrobe's guide for wedding guests ASW's guide to black tie weddings The Silentist's tagged "wedding attire" posts A Permanent style's wedding guest suggestions Style Forum's mangum opus: Practical thoughts on coherent combinations for beginners Black Tie guide to weddings MFA's Putting together a balanced and tasteful outfit MFA's Basic blazer/trouser combinations MFA's British formalwear Search link to MFA tagged "wedding" More on reddit.com

Hot climate weddings are often in white or cream linen or cotton suits. https://www.pinterest.com/search/pins/?q=men%20white%20linen%20suit&term_meta%5B%5D=men%7Ctyped&term_meta%5B%5D=white%7Ctyped&term_meta%5B%5D=linen%7Ctyped&term_meta%5B%5D=suit%7Ctyped More on reddit.com