Travel in Europe in August

Scandanavia is quite costly. Have u thought of Britain? The exchange is the best right now against US dollar. So many great locations and generally temperate weather. There are also reasonable chain hotels like Traveloge UK.
Great for families. I am actually in London as I write. Many free museums in london itself if that interests u.

Try the baltic states it has the mild summer and low prices

Most of the Atlantic coast of Spain tends to be cool in the summer. Barcelona is likely to be hot and muggy, and Madrid will almost certainly be hotter still. But if you're asking "how many countries", you probably would not be interested in spending 3 weeks in northern Spain.

Anywhere well up in the mountains should work--the Alps, the Dolomites, etc. But 3 weeks is a pretty long time to be confined to high-altitude locations. Not a lot of traditional tourist sites up there.

Agree that Scandinavia is very costly. 21 days is a long trip to prepare with just over a month's notice (but sounds awesome). And on # of countries, to me it's more a matter of "home bases" or "cities" because you could easily do Netherlands, Brussels,and France and touch 3 countries in 3 days.

Ireland rarely, if ever, gets ungodly hot even in August. You may get a few 'soft' days with some form of rain or mist. It's way more affordable than Scandinavia. Combine it with a stopover in Iceland, which may be a bit expensive but a good option weather wise. Also I agree that Great Britain is a good choice in August - some combination of England, Scotland, Wales, NI. Most coastal areas will be much more comfortable when it comes to weather than the interior of Europe.

If you want to visit Scandinavia, then Rick's guidebook can help you identify moderately priced options. While comparing apple to apples may be more expensive than other countries, there's also a higher standard among budget accommodation like youth hostels, which have quad rooms for about $110/night. In other parts of Europe, a vacation apartment can be a more common budget option.

What do you want to do as that will have the biggest impact on deciding where to visit?

What about the Baltic coast of Germany and Poland? Or Estonia, Latvia and Lithuania? Or even a combination of all of it! You could start off in Helsinki and experience a flavour of Scandinavia (sort of!) before taking the ferry to Tallinn and working your way down to Mecklenburg, that would combine historical city sights with unspoilt beaches and countryside, the best of both worlds and an amazing opportunity to experience a number of different countries in a relatively hassle free manner.

Ireland and Scotland rarely get hot. I think 75F is considered sweltering. Then there's northern England - lake district, York. I took a 2-week tour of Ireland/Northern Ireland, spent another 5 days in Dublin on my own and would have been happy to stay longer.

You could add London, Belgium (Bruges, Ghent) and Netherlands, which are more likely not to be real hot, though the only sure thing about the weather in August is that it's unpredictable.

Prague, Czech Republic is really cheap and fun. Add a day trip to Kutna Hora ossuary, if your kids like "bones".

Germany is a bus ride away from Prague. Kids would like Rothenburg. Munich is fun, and you can take a train to Zugspitze, where you take a cable car up the mountain, 9000+ feet, and stand on the corner of 4 countries (Italy, Germany, Austria, and Switzerland) while you play in snow!

Also, Plitvice Lakes, in Croatia, looks beautiful, but I haven't been there, yet!

you can take a train to Zugspitze, where you take a cable car up the mountain, 9000+ feet, and stand on the corner of 4 countries (Italy, Germany, Austria, and Switzerland)

So the Italians have secretly conquered Tyrol with the support of the Swiss? ;)

I'd encourage Scandinavia, it's great in August. In fact, I'd only visit the area in July or August. I think the best way to see the area is by sea, historically that's how people got from city to city. You could take a ferry betwen most of the cities and arrange your own itinerary. We flew into Copenhagen for three nights, then got on a Baltic capitals cruise (Princess) that included Stockholm, Helsinki, St. Petersburg (2 days), Tallinn, Gdansk, Oslo, then back to Copenhagen for another three nights before flying home.

Look for some last minute cruise deals at vacationstogo.com. They're an online agent and specialize in cruises. I've booked with them at least three times and never had an issue. I recommend them because their search engine is the best of the online agents. Some of the last minute deals beat the cost of food, transportation and lodging (all included in your fare) by quite a bit.

You can get relatively cheap flights through Iceland right now (Wow Air, but Icelandair has to compete with them), so you could also plan a few days stopover in Iceland on your way home.

I thought Copenhagen was a great base. There's more to do in and around Copenhagen than anywhere else in Scandinavia. If you stay in the Nyhaven area, take the metro from the airport. It takes maybe 15 minutes. The train downtown takes longer (maybe 20 minutes) and Nyhaven is a much nicer area to base yourself.

If not there, the beaches on the north coast (Atlantic) of Spain are good that time of year. Other times they're rainy and chilly.

If you want affordable, Scandanavia is pretty much out. I second the UK/Ireland suggestions but another potential is combining the UK with Normandy and Brittany in France. I was there in August and the hottest it got was the high 70s. It's my understanding that the Atlantic Coast of France has similar weather to the UK (i.e. mild summers), and it would be fun to take a ferry over from England, then rent a car. Both areas are stunning and of course the historical sites of the D Day Beaches and the Bayeux Tapestry aren't to be missed. Prices are even cheaper there than the UK, and honestly the UK is a lot cheaper once you leave London. I could spend weeks in this area, honestly, I just love the food and the scenery.

In the UK, we visited Yorkshire last August and had an amazing time. We hiked the moors, based out of Pickering, then spent a few days in seaside Whitby, which would be a fabulous area to explore with more time, and then spent a few days in York, which was an amazingly atmospheric historic city. The people of Yorkshire couldn't haven't been friendlier. One of our favorite trips ever. And we managed to do it without renting a car (we have no interest in trying to drive on the other side of the road, thank you.)

But really there are so many fabulous places to go in the UK that you could have a wonderful time anywhere!

I am currently in northern France and there is little here that is cheaper than England, except for petrol and wine. Eating out is considerably more expensive in France and most meat is double UK prices. We have also had 3 days of almost solid rain and it's only 13 degrees (55 F) in the middle of the day!

Scandanavia is more expensive again and at such short notice, the best value places will have gone by now.

Coastal Europe will be cooler than inland. Northern Portugal and Spain would be cooler and good value. Portugal could be combined with Madiera or the Azores. The UK and Ireland will be cooler, although Ireland will be more expensive.

The Baltic States are cheaper and you could visit a couple of countries in three weeks.

If you want it to be memorable, I always find that less is more, so take your time and enjoy!

At Zugspitze you have a simple Germany/Austria border. The closest thing to what you are thinking is near Reschenpass where Italy, Switzerland and Austria meet (the actual border point is fairly difficult to access).
Austria is a cozy place and it is not super hot if you manage to keep to some elevation - for example Innsbruck is relatively hot but its nearby villages are not. And you can find accommodation at much better prices than Scandinavia and Switzerland. August is the most crowded month so the best options are likely to be already reserved.

I don't know where in north France you are, Jennifer, or what kind of restaurants you're eating at, but we sustained ourselves quite well on buckwheat crepes in Normandy and Brittany for 6 euros a pop.