Day and night
With Day cycle enabled, one complete cycle takes 900 seconds of active world simulation: fifteen minutes. Creature night logic uses the clock before approximately 0.23 and after 0.78. Settings can disable the cycle.
Night can bring dangerous terrestrial mobs, and the unified mermaid becomes its siren form. Creator still allows naturally occurring hostile mobs, while preventing them from selecting or retaliating against the player. Stasis remains the peaceful choice. Many ordinary animals sleep at night; foxes, wild wolves and cats have a daytime sleep window. Threats, water, breeding, riding and meals interrupt sleep.
Rain, storm and fog
Weather supports Clear, Rain, Storm and Fog. Exposed materials darken and gain a wet sheen, then gradually dry after rain. This is shared weather wetness with shelter shading, not a separate saved wet value for every voxel.
A solid roof, including glass, stops rain even if it transmits light. Roof edits refresh the rain-cover checks. Covered torches stay lit. An exposed torch can become unlit in rain, remains placed, and can be relit with a fire striker when conditions permit. Rain can extinguish loose flames. Campfires are contained; loose fire can consume nearby timber.
Flooding
Storms occasionally place real temporary water on loaded low shoreline land near existing surface water. It can wash out plants and crops, carry bodies with currents, and drown land animals. Seek higher ground and give livestock a dry exit. Receding water does not restore every washed-out crop.
The current event considers terrain at sea level or one block above it, skips overhead-covered cells, and places at most 384 initial temporary sources. Their timer is about 45 active seconds, and recession survives saving/reloading. This is local budgeted flooding, not global tides or a full hydrodynamics simulation.
Lightning
Lightning has a physical strike location, nearby body damage, distance-delayed thunder and occasional small fires. Rain may extinguish those fires. The player is not deliberately chosen as the target. Treat lightning as a world event, rather than only a harmless screen flash.
Sky
Moon phases clip the unlit surface into crescents, quarters and gibbous forms. The current night sky has irregular sharp stars and a faint blue-violet Milky Way with dark dust lanes. Clouds hide stars; daylight, mist and rain suppress them. A full moon dims the Milky Way, and stars do not draw while you are submerged. The sky is stylized procedural art, not an astronomical catalogue.