How to fix “Bad URI (is not URI?)”

This URL contains special characters, which Ruby can’t handle:

URI.parse 'http://www.yr.no/sted/Finland/Västra_Finland/Askainen/varsel.xml'

URI::InvalidURIError: bad URI(is not URI?): http://www.yr.no/sted/Finland/Västra_Finland/Askainen/varsel.xml
   3  	from /usr/local/lib/ruby/1.8/uri/common.rb:436:in `split'
   4  	from /usr/local/lib/ruby/1.8/uri/common.rb:485:in `parse'
   5  	from (irb):5

Your browser can probably open the URL. To fix this error encode the URL before handing it to the parse method:

 URI.parse(URI.encode('http://www.yr.no/sted/Finland/Västra_Finland/Askainen/varsel.xml'))
   2  => #<URI::HTTP:0x18bfb40 URL:http://www.yr.no/sted/Finland/V%C3%A4stra_Finland/Askainen/varsel.xml>