Clouds in the Forecast

The Sifrei says that Bnei Yisrael brought the Korban Pesach only once during their 40-year sojourn in the desert. This Sifrei says further that this reflects badly on Klal Yisrael.
Tosafos wonders why they didn’t bring the Korban Pesach all those years. He finds it unfathomable to suggest they willfully violated a mitzvah for no cause. Instead, Tosafos says to blame it on the weather. The halachah is that uncircumcised males are not allowed to partake of the Korban Pesach. Further, both mothers and fathers of boys without a bris milah are likewise not allowed to partake of the Korban Pesach (see Rashi Yevamos 71b). The Gemara states that bris milah was not practiced during all those years they traveled in the desert. The bris milah would have put the baby boys in danger.
Traveling itself takes a toll on a young child’s health, and this would be further exacerbated by the bris milah. Moreover, the Gemara states that the weather was somewhat harsh during those years. According to Tosafos, the harsh weather was a punishment for the sin of sending spies to Eretz Yisrael. Perhaps during those years, most of Klal Yisrael had uncircumcised sons, and therefore they could not bring the Korban Pesach.