The short answer to your question should be no, you do not need to file an FBAR form, if you are a Swiss citizen temporarily in the United States. A longer answer to your question is more detailed, so please continue reading if you wish.
There are actually (2) separate foreign financial account disclosure forms that can be applicable to US citizens, resident aliens, and nonresident aliens (and your self-described circumstances would seem to place you in the nonresident alien category).
These (2) different disclosure forms; each also has different
reporting rules. One is known as IRS Form 8938, which is filed along with a US income tax return. The other is FinCen
Form 114, which can only be filed via a specific government site on the internet. The following
Internal Revenue Service (IRS) webpage describes both of these disclosure documents in some detail, and provides
their US dollar value reporting levels:
https://www.irs.gov/businesses/comparison-of-form-8938-and-fbar-requirements
After visiting that link, you can see from reading the IRS summary there that FBAR (a.k.a. FinCen Form 114) does not apply to nonresident aliens. In other words, nonresident aliens are exempt from FBAR.
Form 8938 disclosure requirements can apply to nonresident aliens, but only those who make an election to be treated as a resident alien for purposes of filing a joint income tax return, along with a US citizen or US resident alien; or those nonresident aliens who are a bona fide resident of either American Samoa or Puerto Rico.
Since you are a Swiss national (and temporarily in the United States), none of this applies to you. Thus, you do not need to file either Form 8938 or a FinCen 114 (FBAR) disclosure.
Thank you for asking this question.
