1,341. If the Moon is Never Seen

Hilchos Kiddush HaChodesh 18:6

(Continued from halacha 18:5) The court counts 29 days from Rosh Chodesh of the second month but the moon is not seen. If you think that a day should again be added to the month so that Rosh Chodesh of the third month will be the 31st day, as it was in the second month, consider: it’s possible that the moon may not be seen on the 30th night of this month, either. We could potentially enter into a situation in which a day is added and the new month begins after 30 days every month of the year. In such a case,  the moon might end up being seen on the night of the 25th or the 26th of the last month. This would be utterly ridiculous and would undermine the entire system.

Hilchos Kiddush HaChodesh 18:7

One can’t say that the moon never being witnessed throughout the year is too unlikely to worry about. Just the opposite, it’s actually quite likely! Such is often the case in countries with long winters and lots of clouds. The idea isn’t that the moon is never seen, just that it might not be seen at the beginning of the month (as is necessary to declare Rosh Chodesh). The moon might not be witnessed either because doing so is impossible or, in months when it is possible, because of cloud cover or because the visible portion was so small that no one paid attention to it.