When the level of the lava in the crater plummets, as geologists are seeing on Kilauea, that can be a sign that explosions of ash and steam could follow.
The level of the lava lake in Kilauea's summit crater has fallen over 220 meters in recent days, indicating an explosion is likely.
Residential neighborhoods near Kilauea's crater have been hit particularly hard.
The volcanic activity causes rifts, or fissures, to open in the ground around the crater, causing lava to spew out into residential neighborhoods.
When there's precipitation in the forecast, sulfur dioxide can also cause acid rain, when the moisture in the air mixes with the gas.
Acid rain is rainfall that's made acidic by atmospheric pollution like sulfur dioxide. It can kill plants and animals and degrade infrastructure.
Residents are allowed to access their homes during the day, but authorities have warned that they should be ready to flee at a moment's notice.