Even though the weather effects are pretty thoroughly-defined in-game, they have other effects in a more realistic setting. There are a few effects that are added because of this at Maiara, plus some new conditions that were not considered in the games.

Yes, I have a little form for this, too, to make it easier. Here's how it works:
Description: What the weather effect is--more specific than the basic words
Move(s): What moves trigger it
Location(s): Where it is most likely to be found on Maiara
Effects: List of effects it causes

Bright Sunlight
Description: Clouds clear the area and the sun's rays are focused on the battlefield.
Move(s): Sunny Day, Morning Sun
Locations: Burning Sands, Ruin Oasis, Fire Mountain, Moving Dunes, Gray Wastes, The Sparkling Beach, Reluctance Cove
Effects:
-Increases power of Fire-type moves by approximately 50%
-Decreases power of Water-type moves by approximately 50%
-Decreases accuracy of Thunder to about 50%
-Allows instant use of Solarbeam
-Synthesis and Morning Sun can recover all HP
-Pokémon with the Chlorophyll ability have their Speed increased
-Pokémon with the Dry Skin ability gradually lose health
-Activates Cherrim's Flower Gift ability (if that will ever happen here)
-Pokémon with the Leaf Guard ability are immune to status changes (Poison, Paralyze, etc) and, upon activation, have all statuses cured
-Pokémon with the Solar Power ability have their Special Attack increased, but lose health

Rain
Description: Clouds have gathered and rain has begun.
Move(s): Rain Dance
Locations: The Tropical Forest, Mizzelan Forest, The Channel of Trials, Evostone Isle
Effects:
-Increases power of Water-type moves by approximately 50%
-Decreases power of Fire-type moves by approximately 50%
-Increases accuracy of Thunder, and may allow it to break through Protect
-Increases charging time of Solarbeam
-Synthesis, Morning Sun, and Moonlight are less effective
-Pokémon with the Dry Skin ability recover health gradually
-Pokémon with the Hydration ability are immune to status changes and, upon activation, have status conditions cured
-Pokémon with the Rain Dish ability slowly recover health
-Pokémon with the Swift Swim ability have their Speed increased
-Mud may lower the Evasion chances of non-Water-types

Thunderstorm
Description: Dark clouds have gathered, causing lightning and thunder, and possibly rain.
Move(s): None
Locations: See Rain
Effects:
-All normal Rain effects if it is raining
-All normal Hail effects if it is hailing
-Pokémon with the Lightning Rod ability may be struck by lightning, damaging them
-Lightning may strike anywhere, damaging those near it

Snow
Description: Water in clouds has frozen into ice crystals, which then fall to the ground.
Move(s): None
Locations: Frozen Beach, Icy Peaks, Cold Forest
Effects:
-Increases accuracy of Blizzard, and may allow it to break through Protect
-Decreases effect of Synthesis, Morning Sun, and Moonlight
-Pokémon with the Ice Body ability gradually recover health
-Pokémon with the Snow Cloak ability have their Evasion increase
-May cause non-Ice-types to lose their footing if the snow gets deep and decrease their Evasion or Speed

Hail
Description: Strong updrafts have repeatedly frozen water into balls of ice, which then fall.
Move(s): Hail
Locations: Icy Peaks
Effects:
-All normal effects of Snow
-All non-Ice-types take damage gradually

Sandstorm
Description: Strong winds cause large amounts of sand to blow about.
Move(s): Sandstorm, Tailwind (in desert)
Locations: Burning Sands, Moving Dunes
Effects:
-All non-Rock-, Ground-, and Steel-types take damage gradually
-Rock-type Pokémon have their Special Defense increased
-Solarbeam's power is reduced
-Thunder's accuracy is reduced
-Decreases effect of Synthesis, Morning Sun, and Moonlight
-Pokémon with the Sand Veil ability have their Evasion increased

Fog
Description: Frozen water particles float about in the air not far above the ground, obscuring vision.
Move(s): Mist, Haze
Locations: The Tropical Forest, The Twin Pillars, Cold Forest, Icy Peaks, Saraku Rift, The Steamy Jungle, Grand Waterfall
Effects:
-Accuracy of all Pokémon is decreased

Strong Wind
Description: Strong winds blow across the field consistently.
Move(s): Tailwind
Locations: Icy Peaks, Grayrock Pass, Moving Dunes, Scatterwood, Land of Gusts, Thunder Mountain
Effects:
-Accuracy of all Pokémon is slightly decreased
-Lighter Pokémon may be blown about
-If debris is flying about, it may strike and damage Pokémon

Shadow Sky
Description: A shadowy aura is launched into the sky, which gradually dissipates to the ground.
Move(s): Shadow Sky
Locations: None
Effects:
-All non-Shadow Pokémon take damage gradually
-All Shadow Pokémon have their Special Defense increased slightly