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It's 'common knowledge' that certain cities/regions have mild weather because they're surrounded by mountains. E.g. this page Sitges Tourist Guide claims that:

Ask any Sitges resident about the weather in their town and they will proudly tell you about the microclimate in the area. Sitges is protected by mountains, providing it with a climate that is unaffected by surrounding areas. It could be pouring with rain in Barcelona and the sun could still be shining in Sitges.

Likewise a random property in New Zealand claims that:

Here in Tukurua we are protected by mountains from the cold south winds in winter so we enjoy a micro-climate in which snow is unknown, but snowfalls are common in July and August on the mountains surrounding Golden Bay, making for a beautiful backdrop to our wonderful scenery.

I've heard similar claims about even bigger regions, such as whole countries, but I can't find any English-language quotes. E.g. this page mentions that the Czech climate is mild because the country is surrounded by mountains.

Is it true that being surrounded by mountains can make the local microclimate less windy and rainy, as well as more warm?

JonathanReez
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  • First, you have to get rid of such subjective terms as "bad weather". As the answer below states, mountains do have effects on weather. For instance, I live on the east side of the Sierra Nevada, which gets much less rain than the west side. Is this good or bad? I think it's bad because I like rain, and not having to irrigate. Others think differently. – jamesqf Nov 16 '16 at 18:41
  • @jamesqf done. Some websites claim this phenomena exists for regions as big as Czech Republic though. Could this really be true? – JonathanReez Nov 16 '16 at 18:55
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    The US Great Basin has more than 6 times the land area of the Czech Republic, and is 'protected' from excess precipitation by the Sierra Nevada and Cascade mountains. See for instance precipitation maps of the western US: http://www.wrcc.dri.edu/pcpn/westus_precip.gif Or (anecdotal) today, as is often the case, I can look out my window and see it's snowing in the mountains a few miles to the west, but clear here. But the question might get a better answer on the Earth Science site... – jamesqf Nov 17 '16 at 00:26

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Climate can definitely be affected by the presence of mountains. One such occurrence is Rain Shadow, where the peak of the mountain causes the clouds that would normally pass over to raise in altitude, precipicate and rain back down before fully crossing over the mountain, leaving the air behind the mountain dryer.

Rain shadow image by en:User:Bariot - en:File:Rainshadow copy.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=10279370

They also block wind, affect pressure systems, and can funnel stronger winds to certain areas through channels/valleys between mountain peaks, and as such can have a huge effect on the surrounding climate.

James T
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  • Note that the edge of the rain shadow can be surprisingly sharp. For example, one time when I was camping at Mount Rainier, six inches of rain fell on the campground, while White Pass, ten miles and one ridgeline away, remained dry. Another time, the White River valley where I was camped was clear and sunny, while the other side of the ridge was under a heavy overcast. – Mark Nov 19 '16 at 00:20