FANTASY WEATHER GENERATOR 0.18
 
Instructions:
"Tropics" is latitude of 0 to 30 degrees, "Temperate" is 30 to 60, and "Cold" is 60 to 90. As reference: Northern Florida or Northern
Egypt are about 30 degrees North, Southern Alaska or Southern Norway are about 60 degrees North.
System Events Used "Sea Level" is under 1,000 feet (300 m), "Lowlands" is 1,000 to 5,000 feet (1.5 km), "Highlands" is 5,000 to 10,000 feet (3 km),
Measurement System and "High Mountains" is over 10,000 feet (3+ km).
Select Climate "Days" start with Sunrise and end with Sunset. "Nights" start with Sunset and end with Sunrise on the following morning.
Select Season Precipitation events with a sufficiently long Duration should be assumed to span into the start of the following Day or Night and
Select Elevation may cause events listed as Rain to turn into Snow events, or Snow events into Rain, which must be manually tracked.
Desert Biome? Per rules, baseline temperatures are intended to last several days. Generating a low numbers of days will disrupt this.
Stable Temp Biome? Snow accumulation must be tracked manually. Rainfall is not measured. For Pathfinder: 2+ inches (5+ cm) of snow adds 5 feet
Force Precipitation? (1.5 m) of movement cost per square, 12-36 inches (30-90 cm) adds 10 feet (3m) of movement cost per square, 36+ inches
Adjust Temperature? (90+ cm) requires snowshoes for progress. For D20 / D&D 3.5: 1-12 inches (5 cm) adds 5 feet (1.5 m) of movement cost
Weaker Winds? per square, 12+ inches (30 cm) adds 15 feet (4.5 m) of movement cost per square.
# of Days to Generate Thunderstorms and Thundersnow have a low, GM-determined chance of a Lightning Strike on players. For Pathfinder: 1 Strike
Scripting by Christopher Page per 10 minutes possible for Thunderstorm and 1/hour for Thundersnow. Lightning Strikes deal 10d8 Electricity damage,
Based primarily on weather generation rules from Reflex Save DC 18 for half, -4 on save if in metal armor. For D20 / D&D 3.5: Lightning Strikes for Thunderstorm or
Ultimate Wilderness 2017, Paizo Inc.. License: Thundersnow may occur 1/hour dealing (1d10)d8 Electricity damage.
OGL v1.0a . Send suggestions and bug reports to: For Pathfinder: non-specific Skill penalties from Wind apply per GM discretion, possibly stacking with Perception penalties.
cap708g at hotmail. Thunderstorm Wind Speed is listed even when Tornados and Hurricanes are present. Tornado and Hurricane events that occur
  during or after Thunderstorms and must be generated manually.
  Due to days with constant sunlight or darkness, errors may occur for areas near a Pole experiencing Summer or Winter.
Day # Day or Night Cloudcover Wind Speed Temperature Wind Chill Event Event Start Hours Duration
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
Alterations to Published Rules:
Baseline Winter temperature for Tropics was increased to 65 degrees to greatly decrease the chance of frozen precipitation at night.
"Stable Temp Biome?" option was added to decrease temperature variations by either 1/3 or 2/3 for moderate Biomes such as Mediterranean.
"Drizzle" renamed to "Light Rain" and "Rain" renamed to "Medium Rain" to create a consistent naming convention.
"Windstorm" Wind Speed set to 51 to 74 as opposed to "51+" as "Hurricane" threshhold is 75.
"Duststorm" replaces "Sandstorm". Duststorm and Haboop and may occur in Deserts when there are high winds and no Precipitation. Duststorm otherwise follows Rain rules.
Couldcover descriptions changed to "None", "Light", "Medium", and "Heavy" to create a consistent naming convention.
Maximum temperature for "Thunderstorm with Hail" limited to 79 to better mirror such events.
Average Night temperature drop roughly doubled depending on Climate and Biome.
Previously absent Blizzzard effects added by extrapolation from other snow events.
For temperatures and wind with ongoing durations, a twice-daily variation of -5 to 5 was added.
Precipitation frequency for most categories was increased by 5% each due to the common elimination of Fog events by Wind.
Further decrease of Precipitation for "Drought" areas was ignored, as Precipitation Frequency and Intensity were already very low for those areas.
Added "Force Precipitation?" option to manually adjust Precipitation frequncy. Per rules, precipitation events are limited to one per 24-hour block, but often persist into the following 12-hour period.
Added "Adjust Temperature?" option to manually increase or decrease temperatures. The numbers shown are in Fahrenheit but final results can still be in Celcius.
Added "Weaker Winds?" options to decrease frequency of extreme Wind by either 1/3 or 2/3.
Added Wind Chill to output. I invite GMs to use this as the effective temperature when determining cold weather effects on characters outside of shelter.
Eliminated Tornados for Highlands and High Mountains.
Desert temperatures increased moderately for Day and decreased moderately for Night.