Barcelona or Sevilla for 5-6 days

Go to Barcelona and day trip on the train to Sitges for the beach.

Both cities are great places. I would give the edge to Seville. As for beaches, I never saw the benefit to spending time at the beach, I can do that back home in South Georgia.

I agree that both places are nice to visit. With the current drought restrictions in Catalunya I’d head to Sevilla.

If 6 full days do 3 in each with late evening train from 1 to other

I recommend Sevilla in Andalusia.
You can find better beaches in the USA.

I love Seville but would not choose it in mid to late June. It can be miserably hot.

Seville weather -- June 2023

As you can see from the graph, the high temperature was 90F or above every day between June 19 and June 30 last year. Six of those days hit 100F or higher, as did June 15-17.

Use the pull-down box at the right, just above the graph, to display other time periods. Use the Search box at the upper right to see data for other locations.

Summer is a bad time of year to go to Andalucia.

There are also water activities in Barcelona. Read through all the things to do in Barcelona at the official TI website.

Acraven is so right. Andalucia is HOT in June and getting hotter as you get closer to July. There are beaches in Barcelona that you can get to on the metro. I went to one with a local so I can't give you directions. I think the most convenient beach to Sevilla is Cadiz which is over 1.5 hours by train and then a 15-20 minute (or more?) walk to the beach. Water's probably warm in the Mediterranean (Barcelona) than the Atlantic (Cadiz).

I agree with everyone who has commented about the heat in Seville in June. When I was researching our trip, I read trip reports from people who were in Andalusia during the summer months, and they talked about being drenched in sweat after being outside for 10 minutes. I would choose Barcelona over Seville. Barcelona will still be hot but not as hot as Seville. And at least you have the beach to cool off in while in Barcelona.

If you do choose Seville, choose a hotel that has a pool. Sightsee during the early morning hours. Relax and swim during the afternoon, and go out again in the evening. Make sure you have plenty of water with you.

...about "being drenched in sweat after being outside for 10 minutes", well, Barcelona is not much better, huh! ;) Although indeed the temperature is much lower (30sC vs early 40sC in Seville), but humidity can be high (+75%) on certain days, and on those, you're equally drenched in sweat after being outside for 10 minutes in Barcelona too.

Enric, good point. I didn't think about the humidity. I thought Barcelona might be a better choice because it's on the water so hopefully cooler.

I haven't been to Spain in June, but I'd take seriously acraven's advice about how hot Sevilla can be. Plus any beach trip from there would be a project, while a beach trip from Barcelona would be much easier.

You might also want to consider what kind of sightseeing you want to do, since the two cities are quite different. As our guide told us, Barcelona was under Moorish rule for 80 years, Andalucia for more like 800. That affects architecture, food, culture, etc. A guidebook will tell you what there is to see and do in each city. I liked Sevilla more than Barcelona, but it was October and my interests might be very different from yours.

Maybe consider the northwest coast, around Bilbao? I believe they have beautiful beaches and it might be cooler.

My husband and I travelled to Barcelona and Sevilla last July. If beach time is important, Barcelona with a day trip to Sitges (take the train), is easy - we really enjoyed our day in Sitges. Barcelona was a bit cooler than Sevilla, but they were both hot. We made sure to book hotels with a rooftop pool, and at the heat of the day (mid afternoon) we'd head to the the pool. Then after sunset, head out for the evening. Sevilla was our favorite place. Our hotels were Yurbban Trafalgar Hotel in Barcelona, and Hotel Amadeus in Sevilla - both highly recommended. You'll have a great time in either location!

I'm currently in Seville, the weather is perfect for all activities.

june is intolerable after 9.30am unless you lie under an air-conditioner or as suggested in a pool. In my view the best time to visit is beetween November and March.

As mentioned avoid Andalucia in the summer.