Weather Generation

I've intended to create weather generation tables for each climate and game mechanic effects of weather for awhile now. I originally intended to do something like is presented in B10 Night's Dark Terror, with a % roll of 4 possible conditions each for clouds, rain, temperature, and wind. I had extrapolated from the calendar in the modular to create a chart that covered the whole year. Well, I've decided not to use that model. 

While rereading the OSE books, it occurred to me that a partial weather table was already built into the expert game with the variable wind conditions chart and that the chart could be repurposed for other weather conditions. So here I present four weather tables that use the 2d6 roll and descriptions of how PCs are affected by the weather.

Cloud Cover

2 Fog 

no precipitation; roll 1d4 to determine density of the fog: 

1) visibility limited to 1/2 mile; chances of getting lost increase by 1/6; chances of being surprised increase by 1/6; apply a -1 to To Hit rolls for ranged attacks

2) visibility limited to 400 yards; chances of getting lost increase by 2/6; chances of being surprised increase by 2/6; apply a -2 to To Hit rolls for ranged attacks

3)  visibility limited to 200 yards; chances of getting lost increase by 3/6; chances of being surprised increase by 3/6; apply a -3 to To Hit rolls for ranged attacks

4)  visibility limited to 50 yards; chances of getting lost increase by 4/6; chances of being surprised increase by 4/6; apply a -4 to To Hit rolls for ranged attacks

3-5 Clear 

apply a -1 to next Cloud Cover roll; no precipitation; for every hour the skin of a PC is exposed, they take 1d4 damage from sunburn

6-8 Partly Cloudy 

apply a -4 to the Precipitation table

9-11 Cloudy 

apply a +1 to next Cloud Cover roll; apply a -1 to the Precipitation table

12 Overcast 

apply a +2 to next Cloud Cover roll; roll on the Precipitation table; chances of getting lost increase by 1/6

Precipitation

After the type of precipitation is rolled for it may be necessary to determine what time of day the precipitation occurs; this can be done by rolling randomly by the hour or 4-hour watch, or may be determined as the DM sees fit. The DM may also want to roll on this table more than once a day, at every hourly interval, 4-hour watch, or directly after one precipitation type ends.

The PCs may take precautions to remain dry; this may consist of waterproof clothing, taking shelter under partial cover (large trees) or indoors. If the clothes a PC is wearing become completely soaked, that PC suffers the effects of one Temperature grade lower than reality.

Catching Cold: If a PC catches a cold they suffer a -1 on all To Hit rolls, a -1 INT, and a -1 CON. Also any PC with a cold cannot sneak or hide because of their constant sniffling. A cold will last for 2d6 + 2 days; on the last day another CON check is must be made or the cold persists for another 2d6 + 2 days. For each week a PC suffers from a cold there is a cumulative 10% chance that they will contract pneumonia. A PC who is sick with pneumonia suffers an additional -4 STR, -4 DEX, -1 WIS, and -1 CON. Pneumonia lasts for 1d10 + 10 days, at which point the PC must make a CON check or die.

Freezing Temperatures: If the temperature is Cold, Frigid, or Sub-Zero, then precipitation may manifest as snow, hail, freezing rain aka sleet, or a mixture of freezing rain and hail. 

    The amount of snowfall resulting from any level of precipitation is listed as Snow (x"). Snow 3-12" deep will decrease movement by 10/20/30/50; Snow 12-24" deep will decrease movement by 20/40/60/100; Snow greater than 2' deep will decrease movement by 30/60/90/150. 

    Hail will cause damage to any exposed PCs, this is denoted as Hail (x/time).  

    Sleet will cause a PC to suffer the effects of one Temperature grade lower than reality if their skin is exposed to the freezing rain.

    A mixture of freezing rain and hail cause the normal effects of sleet, but only half the normal damage caused by hail.

    Roll a 1d20 and refer to the table below to determine what type of frozen precipitation occurs

Temperature Grade    Rain    Sleet     Mix        Hail    Snow

Cold                               1-15    16-17    18-19       20          -

Frigid or Sub-Zero            -            -           -         17-20    1-16

Thunderstorms: apply +1d4 to Winds table; apply +4 to frozen precipitation roll; 1% chance per hour an exposed PC is struck by lightning causing 8d6 damage to anyone within 10 feet, this is increased to 5% if the PC is holding or wearing metal

2 No Precipitation 

3-5 Sprinkles 

1% chance of Thunderstorm; lasts for 1d6 x 5 minutes; can stay dry if shelter under partial cover; visibility limited to 1/2 mile; chances of being surprised increase by 1/6; must succeed on a CON check or catch Cold; fire is extinguished on a 3/6; Snow (light dusting); Hail (1/30 minutes)

6-8 Showers  

apply a +1 to Winds table; 20% chance of Thunderstorm; lasts for 2d6 x 10 minutes; can stay dry for up to 70 minutes if shelter under partial cover; visibility limited to 400 yards; chances of being surprised increase by 2/6; must succeed on a CON check each hour or catch Cold; chances of getting lost increase by 1/6; fire is extinguished; Snow (1"); Hail (1d4/30 minutes)

9-11 Downpour  

apply a +2 to Winds table; 80% chance of Thunderstorm; lasts for 1d6 +1 hours; completely soaked in 10 minutes; visibility limited to 400 yards; chances of being surprised increase by 2/6; must succeed on a CON check each hour or catch Cold; chances of getting lost increase by 1/6; fire is extinguished; movement decreased by 1/4; Snow (2d6"); Hail (1d8/10 minutes)

12 Drizzle 

5% chance of Thunderstorm; lasts for 24 hours, at the end of 24 hours there is 2/6 chance that Overcast clouds and Drizzle continue for another day; completely soaked in 30 minutes; visibility limited to 400 yards; chances of being surprised increase by 2/6; must succeed on a CON check each hour or catch Cold; chances of getting lost increase by 1/6; fire is extinguished; movement decreased by 1/4; Snow (1d4"); Hail (1d4/30 minutes)

 

Wind Speed

2 Calm

apply a -4 to next Wind Speed roll; Sailing speed reduced to 0; oarsmen gain 3 times normal fatigue

3 Faint Breeze

apply a -3 to next Wind Speed roll; Sailing speed reduced by 2/3

4 Gentle Breeze

apply a -2 to next Wind Speed roll; Sailing speed reduced by 1/2; fog or smoke is cleared in 1 hour

5 Brisk Breeze

apply a -1 to next Wind Speed roll; apply a -1 to the Temperature Grade table; Sailing speed reduced by 1/3; fog or smoke is cleared in 30 minutes; apply a penalty for ranged attack rolls of 0/-1/-2 for short, medium, and long ranges

6-8  Fresh Breeze

apply a -1 to the Temperature Grade table; fog or smoke is cleared in 10 minutes; apply a penalty for ranged attack rolls of -1/-2/-4 for short, medium, and long ranges; fire is extinguished on a 3/6

9 Strong Breeze

apply a +1 to next Wind Speed roll; apply a -1 to the Temperature Grade table; Sailing speed increased by 1/3; fog or smoke is cleared in 1 minute; apply a penalty for ranged attack rolls of -2/-4/-8 for short, medium, and long ranges; fire is extinguished

10 High Wind

apply a +2 to next Wind Speed roll; apply a -1 to the Temperature Grade table; Sailing speed increased by 1/2; fog or smoke is cleared in 1 round; apply a penalty for ranged attack rolls of -4/-8/-16 for short, medium, and long ranges; fire is extinguished; movement(land) against direction of wind decreased by 10/20/30/50

11 Gale

apply a +3 to next Wind Speed roll; apply a -2 to the Temperature Grade table; Sailing speed doubled; fog or smoke is cleared immediately; apply a penalty for ranged attack rolls of -8/-16 for short and medium ranges, missiles will not reach long ranges; fire is extinguished; movement(land) against direction of wind decreased by 30/60/90/150; flying creatures cannot stay aloft more than 10 minutes; Take on Water (10% if seaworthy, 20% if coastal) resulting in movement reduced by 1/3

12 Storm

apply a +4 to next Wind Speed roll; apply a -2 to the Temperature Grade table; Sailing speed tripled; fog or smoke is cleared immediately; apply a penalty for ranged attack rolls of -16 for short ranges, missiles will not reach medium or long ranges; fire is extinguished; movement(land) against direction of wind decreased by 60/120/180/300; flying creatures cannot stay aloft; Take on Water (10% if seaworthy, 20% if coastal) resulting in movement reduced by 1/3, coastal vessels that roll 21-80% are swamped and sink; if in sight of land when storm hits may find safe harbor on 2/6; if encounter land while being driven by storm, 75% chance ship is wrecked

Wind Direction

2 180 degrees 

3 135 degrees left

4 90 degrees left

5 45 degrees left

6-8 Previous/predominant direction

9 45 degrees right

10 90 degrees right

11 135 degrees right

12 180 degrees

Temperature Grade

A PC may mitigate the effects of temperature by putting on or taking off clothing. Any armor or mild winter clothing will increase the effective temperature of a character by 1 grade; heavy winter clothing will increase by 2 grades; and shedding clothes to the point of near nudity will decrease by 1 grade.

Hypothermia: If exposed to cold temperatures a PC must make a CON check at a specified interval of time, denoted as Hypothermia (x units of time). A failed check increases the degree of hypothermia. These are:

Mild - apply a -1 to STR, DEX, and WIS; gain 1 fatigue, gain fatigue at double the normal rate

Moderate - DEX and WIS are halved; gain 4 fatigue, gain fatigue at double the normal rate

Severe - WIS reduced to 3; gain 10 fatigue, gain fatigue at triple the normal rate; 50% chance of passing out immediately and progressing to the next stage 

Apparent Death - unconscious and completely unresponsive, may still be saved if given expert care

Death - the character dies from hypothermia and there is no hope of revival 

Frostbite: If the bare skin of a PC is exposed to cold temperatures for an extended period of time the extremities of that PC will become frostbitten. The time it takes for frostbite to set in is denoted as Frostbite (x time). Each extremity exposed, the hands, the feet, or the face, will receive 1 light wound each when the given time has passed. When the time exposed is doubled each wound will become serious. When the time has tripled each wound will become critical and any adjacent areas, such as the arms or legs, will also receive a light wound from frostbite. When the time has quadrupled the frostbitten extremity will be dead and irretrievable and adjacent areas will continue to suffer the effects of frostbite until the PC is dead or given treatment.

Heat Stroke: If is exposed to high temperatures a PC must make a CON check at a specified interval of time, denoted as Heatstroke (x units of time). A failed check means a character collapses and is disoriented, their WIS and INT being halved, there is also a 50% chance the PC will pass out at this time. If not treated within 30 minutes they will begin losing 1 point of CON every 10 minutes, and die when their CON reaches 0.

2 Sub-Zero

apply a -4 to next Temperature Grade roll; Hypothermia (1 minute); Frostbite (1 turn)

3 Frigid

apply a -2 to next Temperature Grade roll; Hypothermia (3 minutes); Frostbite (3 turns)

4-5 Cold

apply a -1 to next Temperature Grade roll; Hypothermia (1 turn)

6-8 Pleasant

9-10 Warm

apply a +1 to next Temperature Grade roll; double water intake

11 Hot

apply a +2 to next Temperature Grade roll; double water intake; gain 2 times normal fatigue; Heatstroke (1 hour)

12 Scorching

apply a +4 to next Temperature Grade roll; double water intake; gain 4 times normal fatigue;  gain 1 fatigue from resting for 1 hour; Heatstroke (30 minutes)