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Mastering the Wild / Weather in the Wilderness

Weather Details

Source Ultimate Wilderness pg. 169
While temperature and precipitation are important aspects of weather, other details can add further danger and drama. Powerful winds can complicate weather, cloud cover can obscure vision, and special, often destructive weather events can cause incredible mayhem and widespread devastation.

Wind

Source Ultimate Wilderness pg. 170
Once you’ve generated the day’s precipitation, you’ll need to establish the wind strength unless the precipitation indicates otherwise. For example, on foggy days, no significant wind occurs, while thunderstorms have their own rules for determining wind strength. To set the wind strength for the day, roll d% and consult the table below.

Table 4-28: Wind Strength

d%	Wind Strength	Wind Speed	Ranged Weapon Penalty/Siege Weapon Penalty	Check Size	Blown Away Size	Skill Penalty
1-50	Light	0-10 mph	—/—	—	—	—
51-80	Moderate	11-20 mph	—/—	—	—	—
81-90	Strong	21-30 mph	-2/—	Tiny	—	-2
91-95	Severe	31-50 mph	-4/—	Small	Tiny	-4
96-100	Windstorm	51+ mph	Impossible/-4	Medium	Small	-8

Wind Strength: This is the category of the wind strength.

Wind Speed: This is the range of wind speeds that occur. Wind speed typically fluctuates between these values through the period of the day, and for moderate or higher wind strength, there are periods in the day when the wind speed dips below the listed range.

Ranged Weapon Penalty/Siege Weapon Penalty: These are the penalties that characters take when firing ranged weapons and siege weapons in wind of the listed strength. In windstorm-strength wind, normal ranged weapon attacks (either projectile or thrown) are impossible. This includes ranged attacks made via spells of the conjuration school, but it does not include evocation ranged attacks. Siege weapons include all weapons of that type and boulders thrown by giants and other creatures with the rock throwing special attack.

Check Size: Creatures of the listed size or smaller are unable to move forward against the force of the wind unless they succeed at a DC 10 Strength check (on the ground) or a DC 20 Fly check if airborne.

Blown Away Size: Creatures of the listed size on the ground are knocked prone, roll 1d4×10 feet, and take 2d6 points of nonlethal damage, unless they succeed on a DC 15 Strength check. Flying creatures of the listed size are blown back 2d6×10 feet and take 2d6 points of nonlethal damage due to battering and buffeting, unless they succeed at a DC 25 Fly check.

Skill Penalty: This is the penalty for skill checks that can be affected by the wind. These penalties always apply on Fly checks and sound-based Perception checks, but GMs may also wish to apply them on Acrobatics checks, Climb checks, and any other ability or skill checks that could be adversely affected by winds.

Cloud Cover

Source Ultimate Wilderness pg. 171
You can roll on Table 4–29: Cloud Cover to determine the cloud cover for the day. Light and medium cloud cover mainly serve as thematic elements. Overcast conditions grant concealment for creatures flying at high altitudes. Overcast conditions without precipitation increase the temperature in fall and winter by 10° F and decrease the temperature in spring and summer by the same amount. If precipitation occurs, the cloud cover functions as overcast.

Table 4-29: Cloud Cover

d%	Cloud Cover
1-50	None
51-70	Light clouds
71-85	Medium clouds
86-100	Overcast

Severe Events

Source Ultimate Wilderness pg. 171
On rare occasions, weather can produce truly dramatic and dangerous events. The following severe effects are sometimes generated by extreme precipitation. For instance, thunderstorms can create or be a harbinger for haboobs, hail, tornados, wildfires, or even hurricanes. At other times, certain types of precipitation combined with higher wind strengths can generate these severe events.

Blizzard: A combination of severe or stronger winds with heavy snow can create blizzard conditions. Blizzards reduce range of vision to no more than 20 feet, and even then, creatures takes a –8 penalty on Perception checks within that range. In a blizzard, the snowfall increases to 4 inches of snow each hour, and travel in more than 3 feet of snow is usually impossible without snowshoes or an ability such as waterwalk. Furthermore, the high winds make it feel (and affect living creatures) as if the temperature were 20° F colder. There is a 20% chance that a blizzard lasts for 2d12 hours instead of the normal duration for heavy snow. Haboob: A haboob is a sandstorm created by a thunderstorm. See Sandstorm below for its effects. Hail: Hail typically occurs just before or during a thunderstorm. Hail does not reduce visibility, but the sound of falling hail imposes a –4 penalty on sound-based Perception checks. Rarely (5% chance), hail pellets can become large enough to deal 1d4 points of lethal damage per minute to creatures and objects out in the open.

Hurricane: Hurricanes are incredibly massive storms featuring heavy rain and a wind strength greater than that of the most powerful windstorm. With winds of 75–174 miles per hour, a hurricane renders ranged attacks impossible, and siege weapons take a –8 penalty on attack rolls. Large or smaller creatures must succeed at a DC 15 Strength check or they are unable to move forward against the strength of the wind. Medium or smaller creatures on the ground must succeed at a DC 15 Strength check or they are knocked prone and roll 1d6×10 feet, taking 1d6 points of nonlethal damage per 10 feet. Flying creatures must succeed at a DC 25 Fly check or they are blown back 2d8×10 feet and take 4d6 points of nonlethal damage due to battering and buffeting. Hurricanes also usually cause flooding. It’s nearly impossible to journey out into a hurricane unscathed.

Sandstorm: Sandstorms occur when severe or greater winds kick up sand and debris in a desert or similarly arid environment. Sandstorms reduce visibility to 1d10×10 feet, and those within them take a –6 penalty on Perception checks. Sandstorms deal 1d3 points of nonlethal damage per hour to creatures caught in the open.

Thundersnow: High winds in a snowstorm can create the rare phenomena known as thundersnow. Lighting strikes are less common in thundersnow, but just as deadly. Every hour during the storm, a bolt of lightning strikes an unsheltered creature at random (though this can strike wildlife as easily as PCs). A creature struck by this lightning must succeed a DC 18 Reflex saving throw or take 10d8 points of electricity damage (a successful saving throw halves the damage). Creatures in metal armor take a –4 penalty on the Reflex saving throw.

Tornado: With winds with speeds of 174–300 miles per hour, tornados are deadly terrors. The smallest tornados occupy a 20-foot-radius burst, with winds of windstorm strength swirling up to 100 feet beyond that burst. The largest tornados can be 100-foot-radius bursts, with a windstorm whose radius extends 500 feet beyond that burst. Ranged attacks, including normal, siege, and even those produced by evocation spells, are impossible in the core burst of a tornado. Huge or smaller creatures must succeed a DC 20 Strength check or be sucked up by the funnel of the tornado; this deals 8d8 points of bludgeoning, piercing, and slashing lethal damage to the creatures. This damage ignores all but DR/epic, DR/—, and hardness. Once it deals this damage, the tornado flings the creature it has sucked up 1d20×10 feet up and away from the tornado, dealing 1d6 points of falling damage per 10 feet that the creature is flung. Gargantuan and larger creatures take the 8d8 points of damage but are not moved by the tornado. A tornado moves at a speed of 40 feet, though the direction it moves is entirely unpredictable—you can determine the direction randomly each round. Tornados typically last for 3d6 minutes, but some can swirl for up to an hour.z

While most tornados are created by thunderstorms, some smaller tornados (typically with a 5- to 10-foot-burst radius, with no outer radius) can be created in areas of wildfire (firenados), snow (snownados), or sand (dust devils). They deal a similar amount of damage, but firenados deal fire damage, snownados deal cold damage, and dust devils deal bludgeoning damage only, and these types of tornados do not fling their targets.

Wildfire: While wildfires can be sparked a number of ways, for these rules, they are usually created by a lightning strike in a particularly dry area of forest or other vegetation. Use the rules for forest fires, but add a 10% chance of the fire producing 1d6 firenados (see Tornado above).