Prague: too cold for sandals?

Historical averages for those dates are highs in the low 70's and lows in the mid 50's (F) and pretty decent chance of some rain at least one of those days since the average number of days in month of June with some rain is 17.

Usually in late June is sandal weather. I would not hike in Swiss mountains in sandals. I call that pulling devil on his tail.

I like the look of those sandals.. and imagine they would be fine for Prague in june.. however I would not use them for hiking in Switzerland.. trails can still be wet up higher.. and even possibility of a bit of snow left .. so they would be ruined.

I would bring those sandals and a pair of runners ( which will do for simple trail walking type hikes) .. I would also buy both of those before May so I could break them in ..

You may enjoy wearing sandals, but remember Prague has a lot of cobble stoned streets and you need to have good support when walking around the city. I went to Prague in 2006 the end of May into June and it was chilly. I need to wear a jacket. I also would not wear sandals in Switzerland. The mountains could still have snow on the ground and it could be chilly and rainy. Even if is sunny and it could well be, you need the support to hike in Switzerland. You are walking up and going high up in the mountains. I think you should rethink your shoes and bring good comfortable walking shoes that you will not get blisters or wet feet or be uncomfortable. Have a wonderful time. And if your feet are happy, you will be happy!

The most important thing is that they are a good fit for your foot, and that you can walk comfortably all day over all sorts of terrain. Every foot is different, and joint and tendon issues make shoe choices even more specific. If hiking sandals work better for you than boots you will be fine both in Prague and Switzerland in June. Hiking sandals have the added advantage of versatility as they look dressy enough to pass for dinner shoes as well.
I wore these shoes in Prague in cold, rainy fall weather. I have also worn them in snow. They are a perfect fit for me with nonslip soles and the sort of cushioning I need for my osteoarthritic knees. My feet stay warm, and because they are intended for hiking they dry quickly if they get wet. I take along some low-cut socks just in case, but rarely need to use them.
http://www.easyspirit.com/hiking-sandals-splash/58450162,default,pd.html?variantColor=JJ4WOA1&cgid=2881132

I was in Prague at the end of May a few years ago and wore sandals. The temperatures were pretty comfortable, but at that time of year, you never know . I would bring them, but definitely have a non sandal back-up.

Thanks everyone for your replies. It is very appreciated.

I am only taking two pair of shoes and I was hoping both pairs would look cute and be versatile (walking/hiking/dinners with skirts), but I may be asking too much. These shoes have a "hiking" tread on them so I was considering they could do multiple jobs, but if I couldn't wear them hiking then I will have to consider other options. TravelingMom, I really liked the shoe you linked to and will consider that definitely.

This is the 12th pair of shoes I have returned to Zappos! I am well aware of the need for comfortable shoes and then need to break them in, so I am looking exhaustively! Thanks so much for all your help.

Good luck with the search! I like the pair you pointed to a lot, though it sounds as if they may not be ideal for the particular trip you're planning.
I've had other Jambus, and absolutely love them as walking shoes. I've worn mine to Israel, the hills of North Carolina, and Brazil, and even when they got muddy or sandy, all it took was a hose to restore them to their original look.

Prague, unlike California does not have a summer dry season. Average for June-July is 10 to 9 days with measurable precipitation for the month. Teva water sandals would work if you don't mind damp feet.