Dress Codes

From what I recall, no shorts, tank tops, or hats in the Cathedral. The official website of each attraction will have information about what is/isn't allowed.

Wear long loose pants and blouses/shirts. They can actually be cooler than shorts. Look for flowy type pants. Light cotton shirts and blouses are cooler than t-shirts.

Golf pants for men are made to stay cool. For summer touring, my husband used to buy the solid colors, avoiding the plaids.

No shorts. Wear lightweight loose pants and tops.

People in sunny regions long ago figured out covering the skin keeps the sun off, and prevents heating up the body. Loose clothes allow air movement.

Paul, is that why you never see Spanish wearing shorts?

We were just there. Shorts are fine.

The cathedral didn’t permit bare shoulders on ladies and no hats for men.

Basically, dress respectfully. Not hootchie kootchie or looking like it’s time to clean the garage.

Cathedral in Sevilla
Interesting. The official site is pretty vague. Many of the independent sites like ticket resellers (below) are pretty specific and restrictive (appropriate). Then there is one news article of a couple of young ladies that got turned away about six months ago because they showed part of their legs ... didnt go into detial of how short the skirts were. I looked up a few of the sites listed by the OP and the results were the same. The official sites say "appropriate" or "modest" or somethig similar. The non-official sites, the cultural sites and the community sites all say pretty much what is written below.

https://www.seville-cathedral-tickets.com/dress-code/
Seville Cathedral clothing requirements
Keep these clothing requirements in mind before planning a trip to the Seville Cathedral.

Men
Tops: Shirts, t-shirts
Bottoms: Long trousers, jeans, straight-fit pants, chinos
Footwear: Clean and polished formal shoes, closed-toe sports shoes, and loafers.

Women
Tops: T-shirts, shirts, long-sleeve tops. It is crucial to ensure that shoulders are covered at all times.
Bottoms: Knee-length or more skirts and dresses.
Footwear: Closed-toe shoes, low or flat heels, and sports/hiking shoes.

What to not wear to Seville Cathedral
It is worth looking at the list of prohibited attire before visiting the Seville Cathedral to avoid last-minute confusion or the possibility of entry being denied.
Headgear, hats, and caps
Beach shoes
Flip-flops
Tank-tops
Vests
Strapless dresses/tops
Hot pants
Shorts
Mini and short skirts

I was traveling in Turkey the year before in the Summer (equally as hot as Spain), and not only do women need to have everything including hair covered to enter the mosques, you have to remove your footwear.

Not sure why Americans are always focused on shorts as the end all and be all for hot weather.

I agree that loose, light clothing is just as cool, and much more becoming for many people.

Inside the cathedrals is usually more comfortable, as the thick stone walls keep out the strong rays of the sun.

There is a lot of walking, so make sure you have shoes with good support.

Have a great time visiting some of my favorite sights in Spain!

Paul, is that why you never see Spanish wearing shorts?

As an American (in his 30s) with Spanish friends (also in their 30s), I see them and Spanish (men) of their age wearing shorts all the time in Madrid in the summer. I frankly think it's a myth that Spaniards never wear shorts and I don't think the poster is crazy for asking the question.

@Andrew, as an American (with 25+ years in Spain) I can confirm that men of all ages (20's like my son, 40's like some of my coworkers, and almost 60 like me and my friends) wear shorts.

I'll go one better, last Sunday, here in Logroño it was rather hot, and I went to mass in shorts.

As Logroño is on the Camino de Santiago, I can say that many times pilgrims will go to mass in shorts, and at times they look more like they are going to the gym than to a service.

I also agree that the OP isn't crazy for asking the question.

We just got back from our trip and didn't have any problem wearing shorts to any of the places we visited. We saw people with bare shoulders and ass hugging shorts (ours are to our knees) and saw no one being kicked out. Thanks for the kind guidance from those in the post.

Paul, is that why you never see Spanish wearing shorts?

@MrE, when was the last time you went to Spain?

I am in Spain right now and have been here for the past two-weeks-plus.

I can report that I see MANY men and women wearing shorts, and not only to the beach--but walking around town, sitting in cafes, and in restaurants, and at breakfast in hotels.

We've been to very good restaurants every night (or at lunch time) and I was surprised at how many diners were in shorts, more men than women. We had two dinners in a restaurant considered among the finest seafood destinations in Spain, and there, too, many of our fellow diners (again, mostly males) wore shorts, and t-shirts.

Before you ask me the question, yes, I am sure that these people were not foreign tourists. At almost every restaurant we've eaten in the last few weeks, we have been the only non-native-Spanish speakers. We are not, however, in any major city. (We heard people speaking English at a restaurant once, and that was in Santiago, where we began our trip; and we are most definitely not pilgrims!!)

I, too, used to think that the only time Spaniards wore shorts was to the beach.

Either times have changed, or I am more observant that I was on earlier visits.

We had two dinners in a restaurant considered among the finest seafood destinations in Spain, and there, too, many of our fellow diners (again, mostly males) wore shorts, and t-shirts.

It's perfectly acceptable to wear shorts to a restaurant in Spain. Most of the shorts worn are of the smart, tailored type rather than baggy casual ones. I tend to wear smart linen or chino shorts that are above the knee usually accompanied by a short sleeved linen short or smart polo shirt. The stereotype that Spanish men don't wear shorts is completely out of date.

Yes, smart, tailored shorts, not those baggy cargo shorts with the big pockets.
And good shirts, not t-shirts blaring logos of sports teams.

You sound as if you have good taste, JC, or at least the same taste as me as far as fashion!!

As for footwear, I see both men and women wearing sneakers, even to nice restaurants. I have not seen many men wearing sandals.
I've always noticed white sneakers in various regions of Spain, but in Galicia (where we are now) the sneakers tend to be darker (just a fashion comment; I'm not advising anyone what to wear..)

You’ve spent a lot of money to get to Spain and you have timed entry tickets for these sights, correct? So don’t risk being turned away by wearing shorts as you don’t have a second chance. Wear long loose lightweight pants and a loose fitting shirt. Women can wear a longer dress or skirt and use a sweater or shawl to cover their bare arms and shoulders. Most importantly wear good quality sturdy shoes that fit well. If your feet need a break carry lightweight sandals or flip flops in your day pack to change into while you are sipping on a cool beverage

We just got back and we had no problems. We went to several nice restaurants and we didn't feel out of place not wearing a jacket and/or tie. Many people had on shorts. All of the attractions had people who were wearing open toed shoes, shorts, etc.

Great trip!