This is a chart of Random Unusual Weather Phenomena. I’d typically track the weather by rolling for whether the temperature goes up or down from the day before and roll separately if there is precipitation. But on a very unusual roll (maybe 1 in 100) I’d look at one of these two lists:

Phenomena with Potential Game Effects:

Avalanche (not weather, but related): A rapid flow of snow down a slope. It also could be a mudslide or rock-slide. Ball Lightning: It moves slower than normal lighting and can be 8′ in diameter. Blizzard: Not just a heavy snowstorm. An epic once in 10-years storm. Derecho: A straight-line windstorm with a band of strong fast-moving thunderstorms. Diamond Dust: Ground level ice cloud. Dust Devil: Strong whirlwind that is harmless except to creatures in flight. They are a swirling updraft formed in sunny and otherwise calm conditions. Dust Storm (aka Sand Storm): Formed when a gust front picks up dust or sand or other particles in arid and semi-arid regions. Earthquake (not weather, but related): A violent shaking of the ground which can damage buildings or underground areas. It is caused by movements of the earth’s crust. Flood: Can be caused by long, continuous rain, a sudden strong storm, ice-melt from up river or a combination of these. Hail: Frozen ice balls that can be as large as a fist or sometimes larger. It is formed in updrafts of strong thunderstorms. Hurricane/Cyclone: Extreme winds and rain over a large area. Katabatic Winds: Strong winds carrying extremely dense air from higher elevations to lower due to gravity. Limnic Eruption (not weather, but related): Formed when gas (usually carbon dioxide) erupts from underground perhaps under a lake and can cause deaths due to lack of oxygen in the area. Meteor Strike (not weather, but related): A large rock falls from space. Non-Aqueous Rain: Rain made of fish, locusts, or other small animals or insect. Tornado: Concentrated rotating winds of 90+ miles per hour. Tsunami: A tidal wave caused by an underwater earthquake. Volcanic Eruption (not weather, but related): A volcanic eruption can be sudden or with days warning. Lava and clouds of soot are concerns. Wildfire (not weather, but related): A large fire rages a dry area.

Phenomena that Simply Looks Unusual:

Aurora Borealis/Australis: Charged particles from the sun become excited when they reach the upper atmosphere near the poles usually near equinoxes. Colored Moon: Due to smoke, dust or eclipses, the moon can appear to change color. Eclipse (Solar): The moon blocks part of the sun in a solar eclipse. Eclipse (Lunar): The earth shadow blocks part of the moon in a lunar eclipse. Fire Rainbow: Occurs only when the sun is high and its light can penetrate high-altitude cirrus clouds. Halos: A rainbow around the sun caused by the refraction of ice crystals in the upper atmosphere. Lenticular Clouds: Saucer shaped clouds formed when moist stable air flows over a mountain; large standing waves form on the downwind side; and the crest of the wave drops to the dew point. Mammatus Clouds: Network of cloud pouches under the base of a cloud Mirage: Refracted light from objects or the sky on a hot surface. Moonbow: Reflection of the moon’s light when it is full and low. Noctilucent Clouds: Very high clouds that reflect the sun’s light after it has set. St. Elmo’s Fire: Luminous plasma created from an electrical discharge around a pointed object. Occurs occasionally on ship’s masts during thunderstorms or volcanic eruptions. Sun Dog: Bright lights in the sky 22-degrees to the sides of the sun caused by refraction of light by hexagonal ice crystals. Novaya Zemlya Effect: Polar mirage caused by refraction of light through layers of atmosphere. It makes the sun appear to rise early and look rectangular or hourglass-like in shape.

What am I missing? Post a comment with anything else that will fit the list.