Every year, the planet passes very close to the system's asteroid belt. This causes the "fire rain", where meteors from the belt skip across the planet's atmosphere. However, around every 130 years the planet enters a denser part of the asteroid belt, causing the meteors to skip too close to the planet's atmosphere, and even impact the surface. The "Fire rain" in 2000 was the most turbulent in the cycle. One of the meteors buried the Stargate, but SG-1 finally managed to unearth it by using a plasma weapon to create enough of a gap between the gate and the rocks above it for the event horizon to create a larger cavern, allowing Teal'c and Jack to breach the cavern and dig up the Stargate. (SG1: "A Hundred Days")
The next "fire rain" similar to the one in 2000 is due to happen again sometime in the 2130s.