It should fall back to IP geolocation, but you really need to know at least a general location to get accurate times.

If you choose to not share your location, it will ask you to enter an address and it doesn't have to be a full address. Just city name is enough.

My browser is too simple to support location pop up dialogs (it's some lightweight webview wrapper from f-droid with a workflow that I like), I figured it wouldn't work but after a few seconds it fell back to IP based geolocation. Very happily surprised :)

And like someone else already said, street view works fine with a coarse location like a city name, so long as the name is unique and you don't end up in another country.