Weather
There are three types of weather. They have different effects on the world. The weather forecast displays the expected weather for the next five days in advance. Complete final preparations for inclement weather ASAP after they first display in this forecast.
Weather types
Temperate
Temperate can be described as "pleasantly sunny, with zero chance of adverse conditions". It is a time of abundance and renewal for the 
beavers and their lands. 
Water Sources produce pure Water, a life-bringing and life-sustaining natural resource and 
Badwater Sources produce pure Badwater unless controlled with a 
Badwater Rig,
Badwater Dome or 
Badwater Discharge set to closed.
With Water and Badwater flowing through streams, reawakening life in the land, it is time for the Beavers to prepare and stockpile supplies for the ever-approaching Droughts and Badtides.
Drought
Drought can be described as "relentlessly sunny, with zero chance of flowing water".
When Droughts start, Water Sources and Badwater Sources begin to cease flowing. Water and Badwater are not naturally produced again until temperate weather returns. 
Iron Teeth can use a Badwater Discharge to keep Badwater flowing at all times. The only Water and Badwater that exist during a Drought are in 
Tanks or reservoirs.
Evaporation is also a consideration during Droughts. Since sources produce no more Water and Badwater, any fluids on the map may eventually dry up. This leaves Tanks as the last source of fluids during a severe Drought.
Badtide
Badtide can be described as "relentless Badwater, with zero chance of pleasant conditions".
During Badtides both Water Source and Badwater Source emit 
badwater.
When Badtides start, water source contamination begins at 50% and increases to 100% over 12 hours. Similarly, contamination starts decreasing 12 hours before the Badtide ends, dropping to 50% at the end. When temperate weather returns, the 50% contamination immediately drops to 0% as water sources emit pure water.
- Beavers walking or swimming in Badwater may become
contaminated. - Bots cannot become contaminated.
- As contamination levels of polluted water rise, the irrigation range decreases, and the contamination range increases. At 50%, the polluted water neither irrigates nor contaminates. Above 50%, the polluted water contaminates ground with increasing range and actively kills plants. Plants on contaminated ground only survive 0.2–0.3 days.
Mechanics
Event Length
The first Drought and Badtide in a new game on easy and normal difficulties always lasts one day.
The length of Droughts and Badtides increase after each event. The exact timings are based on the Game Mode Settings and some randomness.
The game randomly picks a number between min and max, and then reduces it to that percentage (handicap) value (for cycle 1); I think for subsequent cycles, the handicap is being linearly expanded over the number of handicap cycles, until it reaches 1.00 (100%) once those handicap cycles expire.
Example: On HARD difficulty, the starting handicap is 0.2 (20%), and number of handicap cycles is 15. Drought duration is 15 - 30 days. So, let's say you are very unlucky and the game rolls "30" on a random 16-sided die (with values 15 - 30 on it). Fortunately, 20% of 30 is only 6, so your first drought will be 6 days.
Then, on Cycle 2, you are once again unlucky, the drought duration randomly determined is 28, but fortunately, the handicap is just a little over 20% (one fifteenth of the way from 20% to 100%, so that should be about +5pct --> 25%), so you will get 25% out of 28 = 7 days.
Event Chance
A new game always begins with Temperate weather.
The chance of inclement weather occurring is influenced by both the Settings AND the current streak of consecutive same-weather events. This streak factor applies to both Badtides and Droughts.
Examples: the default chance of Badtide is 40%:
- After five consecutive droughts, the Badtide chance is increased to 70%
- After seven consecutive droughts, the Badtide chance is increased to 100%
The lower the initial Badtide chance, the higher the streak can go before affecting the chance, and vice versa.
Examples:
- A 30% Badtide chance needs eight consecutive droughts before affecting the base chance.
- A 50% Badtide chance needs only four consecutive droughts before affecting the base chance.
Modified chances revert to their default values after the streak is broken.