1,340. Considering the Season and Location

Hilchos Kiddush HaChodesh 18:4

The court should always consider two things: the season when the moon was seen and the location. They should ask the witnesses where they were when they saw the moon because when the arc of visibility is small, there is only a small window in which the moon will be seen. Let’s say, for example, that the arc of visibility was nine degrees, five minutes and the first longitude was 13 degrees, and witnesses claim to have seen the moon. If it’s the summer or if the witnesses were in a low place, we question the accuracy of their testimony and must cross-examine them thoroughly. If it’s the winter or if the witnesses were in a very high place, the moon would certainly be visible unless it was blocked by the clouds.

Hilchos Kiddush HaChodesh 18:5

Let’s say that witnesses saw the moon in its proper time. They come to court and testify; their testimony is accepted so the court sanctifies the month. Later, they count 29 days from this date. On the night of the 30th day, the moon is not seen, either because doing so is impossible or because of cloud cover. In such a case, the court waits for the entirety of the 30th day, as was explained back in halacha 1:6. If witnesses do not arrive, they add a day to the month. Therefore, Rosh Chodesh for this second month is on the 31st day, as was explained there.