1,258. Things That Are Not Reasons to Declare a Leap Year
Hilchos Kiddush HaChodesh 4:6
A leap year is not declared because of snow or cold, or because of Jews from outside Israel who have not yet departed for Jerusalem. If most of the people or most of the kohanim are ritually impure, a leap year is not declared to enable them to purify themselves and to offer the Passover sacrifice in a state of purity. Rather, the offering should be brought in a state of ritually impurity. However, if a leap year was declared because of ritual impurity, it may be left full.
Hilchos Kiddush HaChodesh 4:7
Some things are not sufficient considerations to declare a leap year but they are taken into account when declaring a leap year because of the vernal equinox, the ripening barley or the fruit trees. These are: when young goats or lambs have not been born or are few in number, or young doves are not grown enough to fly. We do not declare a leap year to ensure that goats and lambs will be available for Passover offerings or that doves will be available for pilgrimage offerings and for others who need to bring doves as sacrifices. Nevertheless, these things are taken into account when considering the decision to declare a leap year.