From (http://www.ourbabynamer.com/name-popularity.html) Storm started to be used in the USA since 1946. It could've been given before 1946 because it only shows a number if there are more than 5 given the name.
I've heard this name being used (though rarely) in the Netherlands where it means Storm as well. The Dutch pronunciation is the same except for the r which is a rolling r.
This name is also used in The Netherlands, increasingly so. The Dutch word for 'storm' is 'storm' also, which likely contributes to its growing popularity (since it doesn't appear as a typical English hippie name such as River, but more as a Dutch-style hippie name).
Swedish Pronunciation: STORM.