Can we agree that it will work with 3.3V just fine ?
It is very unlikely that there is some electronics inside the anemometer. So it is just resistors and a contact (it might be a reed switch).
I don't like to wires going directly into pins of the Arduino board. Perhaps some protection resistors in series (in the signal path) is safer. For example 4k7, something between 1k and 10k.