My family, which consists of myself, my husband and our 2 daughters ages 11 and 15, are looking to take a trip in July or August to Portugal and then Spain. From everything I'm reading about Spain, it sounds like it's far too hot to even spend time outdoors during the day. We love to be active and spend time at the beach/hiking/sightseeing/rock climbing, etc. so don't want to be trapped indoors all day. We were looking at areas such as Seville, Malaga, Granada so it's not too far to travel from Portugal. Should we avoid Spain in the summer? If not, what areas in Southern Spain should we consider? What are some must see areas? Thank you in advance for your input! Rhonda

Where are you from and what is your heat tolerance? People do live in these areas, so it's not like it is a no-go zone, but even as someone quite used to hot weather, in July and August I would head to the north of Spain--Porto and then over to Galicia/Asturias for example.
You could finish in the Picos--I am bookmarking lots of ideas for myself (save Andalucia for May--it's perfect the)
Look at this phenomenal place: https://www.turismo.gal/que-visitar/...e?langId=en_US

Not only that people live it that area, it's also one of major vacation destinations in Europe in July and August.
Most visitors will go to any of the many resort towns on the Mediterranean - few will probably go there to do rock climbing, but any kind of beach actitivities will be in full swing. No one goes to Andalucia in summer and stays inside.
Malaga is on the sea, by the way. And had its own city beach.
Granada has a bit higher elevation so it's not that hot.
Otherwise.. well, that's summer.
If you're focused on strenous outdoor activities, other locations like the north of Spain may be better.

As noted, many Spaniards escape to the northern beaches from San Sebastain/Donostia all the way to Gallego coast. There are many beach areas in Galicia which have few people outside of Spain.

Here's a great resource for climate data:
Travel Weather Averages (Weatherbase)

I trust you realize that getting from Portugal to any of the places you mention is not necessarily a snap. You might consider some alternatives before committing. You can check your transportation options on rome2rio.com -- just be sure to click through to the underlying websites, as the main page is not sensitive to seasonal variations.

Is anything booked yet, like airfare? Are you wanting to use public transit or are you planning on driving?

I would rethink this trip if I were you. I think just because Spain is next to Portugal on the map, you think it is easy or quick to get there, and that is why you are pairing these. If you are talking Lisbon, it's maybe 9 hrs by train or something to those areas, like Malaga. If you are flying, you can fly somewhere else in almost the same time, at least just a little more. A nonstop flight from LIsbon to Malaga takes 1:30, but you can get a nonstop on Easyjet to Geneva that takes only 2:15, for example.

Hiking, outdoors stuff, etc, just think maybe Switzerland makes more sense in August.

I personally would never go to southern Spain in August. I don't like beaches in particular, but if I did, peak season when it is sweltering isn't my idea of a fun time on major resort beach areas, either. I've been in Barcelona in July and that was in the 90s, so not too much worse than where I usually go in Europe in summer, but Barcelona isn't nearly as bad as southern Spain.