To determine the present or future weather conditions, follow these steps:
1. Find the Base Temperature for the correct month from the “Temperature Ranges” chart. Roll dice as specified to find the adjustments to the Base Temperature for the day’s High and Low. Adjust both the High and Low Temperatures for terrain and for latitude.
The High Temperature will occur about one hour after mid-day, and the Low Temperature will occur about one hour before Sunrise.
The possibility of temperature extremes may be added by the following;
Before checking for the monthly Base Temperature on the “Temperature Ranges” chart, roll percentile dice and consult this table-
Temperature Extremes
% Dice Rol | Base Temperature Modification |
---|
01 | Extreme Record Low |
02 | Severe Record Low |
03-04 | Record Low |
05-96 | Normal Temperature |
97-98 | Record High |
99 | Severe Record High |
00 | Extreme Record High |
During a Record High or Low, the Base Temperature is the monthly base Temperature plus or minus the maximum high or low possible for the month. Severe Record Highs or Lows are calculated the same way, only using twice the maximum high or low. Extreme Record Highs or Lows use triple the maximum high or low. Once the new Base Temperature is calculated, then the daily Highs and Lows are calculated normally.
The length of time the Temperature Extreme lasts is determined by the following table-
Duration of Temperature Extreme
% Dice Roll | Duration |
---|
01-05 | 1 day |
06-15 | 2 days |
16-50 | 3 days |
51-70 | 4 days |
71-85 | 5 days |
86-95 | 6 days |
96-00 | 7 days |
Temperature Ranges
Month | Base Temperature | Daily High | Daily Low | Precipitation | Midmonth Sunrise | Midmonth Sunset |
---|
1 | 48 | +d10 | -d20 | 46% | 7:05 | 4:45 |
2 | 50 | +d6+4 | -(d10+4) | 40% | 6:39 | 5:20 |
3 | 58 | +d8+4 | -(d10+4) | 44% | 5:56 | 5:53 |
4 | 68 | +d10+6 | -(d8+4) | 42% | 5:08 | 6:23 |
5 | 79 | +d10+6 | -(d10+6) | 42% | 4:29 | 6:54 |
6 | 87 | +d8+8 | -(d6+6) | 36% | 4:16 | 7:16 |
7 | 93 | +d6+4 | -(d6+6) | 33% | 4:29 | 7:13 |
8 | 91 | +d4+6 | -(d6+6) | 33% | 4:57 | 6:41 |
9 | 84 | +d8+6 | -(d8+6) | 33% | 5:26 | 5:54 |
10 | 73 | +d10+5 | -(d10+5) | 36% | 5:56 | 5:05 |
11 | 62 | +d10+6 | -(d10+4) | 40% | 6:30 | 4:29 |
12 | 49 | +d8+5 | -d20 | 43% | 7:03 | 4:20 |
Baseline Latitude is 24
o.
For every 1
o North of the baseline:
- Subtract 1o from Base Temperature.
- Add 1 minute to Sunrise and Sunset times.
For every 2
o South of the baseline:
- Add 1o from Base Temperature.
- Subtract 1 minute to Sunrise and Sunset times.
1
o Change in Longitude causes a 4 minute change in Sunrise and Sunset times.
Midnight Sun Effects:
- At 66.5o Latitude;
- No Sunrise at mid-Winter
- No Sunset at mid-Summer
- For every 1o latitude north of 66.5o, add 3 days to the length of time (1 1/2 day before and 1 1/2 day after).
Terrain Effects Table
Terrain Type | Precipitation Adjustment | Temperature Adjustment | Wind Speed | Special Weather |
---|
Hills | - | - | +/- 5 mph | - 01-80: Windstorm
- 81-00: Earthquake
|
Forest | - | -5 | -5 mph | - 01-80: Quicksand
- 81-00: Earthquake
|
Jungle | +10% | - | -10 mph | - 01-60: Rainforest downpour
- 61-80: Quicksand
- 81-00: Earthquake
|
Swamp or Marsh | +5% | +5 | -5 mph | - 01-25: Quicksand
- 26-80: Sun Shower
- 81-00: Earthquake
|
Plains | - | - | +5 mph | - 01-50: Tornado
- 51-00: Earthquake
|
Desert | -30% | +10(day), -10(night) | +5 mph | - 01-25: Flash Flood
- 26-50: Sandstorm
- 51-65: Oasis
- 66-85: Mirage Oasis
- 86-00: Earthquake
|
Mountains | - | -3 per 1000 feet elevation | +5 mph per 1000 feet elevation | - 01-20: Windstorm
- 21-50: Rock Avalanche
- 51-75: Snow Avalanche
- 76-00: Earthquake
|
Seacoast (within 48 mi. of coastline) | +5% | -5(cold current), +5(warm current) | +5 mph | - 01-80: Earthquake
- 81-00: Tsunami
|
At Sea (more than 24 mi. from coastline) | +15% | -10(cold current), +5(warm current) | +10 mph | - 01-40: Tsunami
- 41-00: Undersea Earthquake
|
No Monsoon or Tropical Storm permitted in Plains.
No Fog, Mist, Blizzard, Monsoon, Tropical Storm, Gale, or Hurricane permitted in Desert.
Duration of Fog and Mist doubled At Sea.
2. Roll percentile dice to determine if precipitation will occur (Temperature Ranges Table). This roll is affected by terrain. If there is no precipitation, roll d20-1 for wind speed and adjust for terrain. Consult the “Wind Chill Table” if necessary.
Wind Chill Table
Wind Speed (mph) | Temperature | | | | | | | | | | | |
---|
| 35 | 30 | 25 | 20 | 15 | 10 | 5 | 0 | -5 | -10 | -15 | -20 |
5 | 33 | 27 | 21 | 16 | 12 | 7 | 1 | -6 | -11 | -15 | -22 | -28 |
10 | 21 | 16 | 9 | 2 | -2 | -9 | -15 | -22 | -27 | -31 | -37 | -43 |
15 | 16 | 11 | 1 | -6 | -11 | -18 | -25 | -33 | -40 | -45 | -51 | -58 |
20 | 12 | 3 | -4 | -9 | -17 | -24 | -32 | -40 | -46 | -52 | -58 | -64 |
25 | 7 | 0 | -7 | -15 | -22 | -29 | -37 | -45 | -52 | -58 | -65 | -72 |
30 | 5 | -2 | -11 | -18 | -26 | -33 | -41 | -49 | -56 | -63 | -70 | -78 |
35 | 3 | -4 | -13 | -20 | -27 | -35 | -43 | -52 | -60 | -67 | -75 | -82 |
40 | 1 | -4 | -15 | -22 | -29 | -36 | -45 | -54 | -62 | -69 | -76 | -83 |
45 | 1 | -6 | -17 | -24 | -31 | -38 | -46 | -55 | -63 | -70 | -77 | -84 |
50 | 0 | -7 | -17 | -24 | -31 | -38 | -47 | -56 | -64 | -71 | -78 | -85 |
55 | -1 | -8 | -19 | -25 | -33 | -39 | -48 | -57 | -65 | -72 | -79 | -86 |
60 | -3 | -10 | -21 | -27 | -34 | -40 | -49 | -58 | -66 | -73 | -80 | -87 |
If precipitation will occur, roll on the “Precipitation Occurrence Table”. If a Special Weather Phenomenon is indicated, roll on the “Precipitation Occurrence Table” again to determine the more normal form or precipitation that will be occurring with the special weather phenomena.
Precipitation Occurrence Table
Roll | Type of Weather | Required Temp. Min | Required Temp Max. | Chance of Continue | Chance of Rainbow | Not Allowed in |
---|
01-02 | Heavy Blizzard | - | 10 | 5% | - | Desert |
03-05 | Blizzard | - | 20 | 10% | - | - |
06-10 | Heavy Snowstorm | - | 25 | 20% | - | - |
11-20 | Light Snowstorm | - | 35 | 25% | 1% | - |
21-25 | Sleetstorm | - | 35 | 20% | - | - |
26-27 | Hailstorm | - | 65 | 10% | - | Desert |
28-30 | Heavy Fog | 20 | 60 | 25% | 1% | Desert |
31-38 | Light Fog | 30 | 70 | 30% | 3% | - |
39-40 | Mist | 30 | - | 15% | 10% | - |
41-45 | Drizzle | 25 | - | 20% | 5% | - |
46-60 | Light Rainstorm | 25 | - | 45% | 15% | - |
61-70 | Heavy Rainstorm | 25 | - | 30% | 20% | - |
71-84 | Thunderstorm | 30 | - | 15% | 20% | - |
85-89 | Tropical Storm | 40 | - | -20% | 10% | Desert, Plains |
90-94 | Monsoon | 55 | - | 30% | 5% | Desert, Plains |
95-97 | Gale | 40 | - | 15% | 10% | Desert |
98-99 | Hurricane or Typhoon | 55 | - | 20% | 5% | Desert |
00 | Special | - | - | 1% | - | - |
3. Once the type of precipitation is known, consult the “Standard Weather Table” or the “Special Weather Table” to discover the effects the weather will have on wind speed, visibility, etc. When the duration of the precipitation expires, roll the Chance of Continuing or lower. If the roll is made, roll for the duration of the precipitation again, and consult the following chart:
Change in Precipitation
d10 roll | Result |
---|
1 | Move up one line on the “Precipitation Occurrence Table” |
2-9 | No change |
0 | Move down one line on the “Precipitation Occurrence Table” |
|
Standard Weather Table
Weather | Amount (in.) | Duration | Movement Rate | Wind Speed | Vision Range Normal | Vision Range Infravision | Tracking | Chance of Getting Lost | Special Effect |
---|
Hvy. Blizzard | 2d10+10 | 3d8 Hours | F:/8, H:/4, C:NA | 6d8+40 | 2’ | 0 | NA | +50% | Snowdrifts of up to 10’/hour may accumulate |
Lt. Blizzard | 2d8+8 | 3d10 hours | All/4 | 3d8+36 | 10’ | x1/2 | -40% | +35% | As Hvy. Blizzard, but at 5’/hour |
Heavy Snow | 2d8+2 | 4d6 hours | All/2 | 3d10 | x1/2 | x1/2 | -25% | +20% | Drifts of 1’/hour if Wind Speed > 20 mph |
Light Snow | d8 | 2d6 hours | F: x3/4 | 4d6 | x3/4 | x3/4 | -10% | +10% | Drifts of 1’/hour if Wind Speed > 20 mph |
Sleet | d2 | d6 hours | F: x3/4, H:/2, C:/2 | 3d10 | x3/4 | x3/4 | -10% | +5% | - |
Hail | - | d4 hours | All x3/4 | 4d10 | - | - | -10% | +10% | Size of stones d4/2. 1 pt dmg/1/2”/turn AC 6 or worse. |
Hvy. Fog | - | d12 hours | All/4 | d20 | 2’ | x1/2 | -60% | +50% | - |
Lt. Fog | - | 2d4 hours | All/2 | d10 | x1/4 | x3/4 | -30% | +30% | - |
Mist | - | 2d6 hours | - | d10 | - | - | -5% | - | - |
Drizzle | 1 | d10 hours | - | d20 | - | - | -1%/turn | - | - |
Lt. Rain | d3 | d12 hours | - | d20 | - | - | -10%/turn | - | Temp. drop of 30 degrees may cause Icing |
Hvy. Rain | d4+3 | d12 hours | F:x3/4, C:x3/4 | 2d12+10 | x3/4 | x3/4 | -10%/turn | +10% | Temp. drop of 30 degrees may cause Icing |
Thunderstorm | d8 | d4 hours | All/2 | 4d10 | x3/4 | x3/4 | -10%/turn | +10% (+30% if horsed) | Lightning 1/turn, 1% chance of being hit, 10% if under trees. 6d6 dmg. |
Tropical Storm | d6/day | d3 days | F:/4, H:/4, C:NA | 3d12+30 | x1/2 | x1/2 | NA | +30% | Every 3 turn, 10% of Gust damage if Wind Speed > 40 mph. d6 dmg/full 10 mph over 40 |
Monsoon | d8/day | d6+6 days | F:/4, H:/4, C:NA | 6d10 | x1/4 | x1/4 | NA | +30% | Every 3 turn, 10% of Gust damage if Wind Speed > 40 mph. d6 dmg/full 10 mph over 40 |
Gale | d8/day | d3 days | F:/4, H:/4, C:NA | 6d8+40 | x1/4 | x1/4 | NA | +20% | Every 3 turn, 10% of Gust damage if Wind Speed > 40 mph. d6 dmg/full 10 mph over 40 |
Hurricane | d10/day | d4 days | F:/4, H:/4, C:NA | 7d10+70 | x1/4 | x1/4 | NA | +30% | |
(F:= Foot Travel, H:= Mounted Travel, C:=Cart Travel, NA= Not Allowed)
Special Weather Table
Weather | Amount (in.) | Duration or Area | Movement Rate | Wind Speed | Vision Range Normal | Vision Range Infravision | Tracking | Chance of Getting Lost | Special Effect |
---|
Sand Storm | - | d8 hours | NA | 5d10 | 0 | 0 | NA | +80% | 50% chance of d4 dmg every 3 turns until shelter is found |
Wind Storm | - | d10 hours | All/2 | 8d10+20 | x1/2 | x3/4 | NA | +30% | 50% chance of 2d6 rock damage every 3 turns, Save vs. Dex for 1/2 dmg. |
Earthquake | - | d10 hours | F:/4, H:/4, C:NA | - | - | - | -50% | +10% (+30% if horsed) | Epicenter is d100 miles away, w/ shock waves extending d100x10 miles. First shock wave preceded by d4 mild tremors. These tremors cause no damage, but will cause untrained animals to flee to open ground. After d6 rounds, first shock wave hits. There are d6 shock waves d20 rounds apart. Effects are same as Cleric Prayer Earthquake. |
Avalanche | 5d10 | d10 minutes | May be blocked | - | - | - | -60% | +10% if trail covered | Dmg 2d20, Save vs Dex for 1/2 dmg. Creatures taking more than 20 pts dmg are buried and will suffocate in 6 rounds. |
Tsunami | Wave height 10d20’ | d2 hours | - | 5d10+10 | - | - | NA | - | Dmg 2d20, Save vs. Dex for 1/2 dmg. |
Quicksand | - | d100x2’ radius | - | - | - | - | NA | +20% if skirted | Creatures wearing Elven chain or lighter will sink only up to neck if all heavy items are discarded and arms kept above surface. Others dragged under at 1 foot per round if still, 2 ft/round if struggling. Drowning occurs 3 rounds after head is submerged. Rescued characters take d6 dmg per round that head is submerged. |
Flash Flood | see below | d6+2 hours | All x3/4 | - | - | - | -5%/turn | +10% | Begins as Heavy Rain (w/ appropriate effects) and drops 3” water per hour. Rain stops when duration is half over. All low areas covered to depth of triple rainfall. Water remains for d5+5 turns, then drops 3”/hour. Current is 5-50 mph depending on channel. |
Rain Forest Downpour | 1/hour | 3d4 hours | F:/2, H:/2, C:NA | d6-1 | x3/4 | x3/4 | -5%/turn | +20% | Ground absorbs 6” of rainfall, then turns to mud. Terrain is now Swamp for purposes of movement. |
Sun Shower | 1/2 | 6d10 minutes | - | - | - | - | - | - | 95% chance of Rainbow. |
Tornado | 1/hour | 5d10 hours | NA | 300 | x3/4 | x3/4 | NA | +40% | 10% chance party transported to Ethereal Plane. Otherwise treat as tripe strength hurricane for damage. |
Oasis or Mirage | - | d3x10’ radius | - | - | - | - | - | - | If real roll d20. 1-2 indicates inhabitants. 20 indicates poisoned water. Anyone who “drinks” from a mirage takes d6 damage from swallowing hot sand (Save vs. Spell to avoid). |
|
(F:= Foot Travel, H:= Mounted Travel, C:= Cart Travel, NA= Not Allowed)
4. Any time that the temperature falls below 35 degrees, consult the “Wind Chill Table”.
5. When precipitation ends, check for occurrence of a rainbow on the “Precipitation Occurrence Table”.
6. When the DM needs the position of a phenomena, roll d8:
Random Direction
Roll | Direction |
---|
1 | North |
2 | Northeast |
3 | East |
4 | Southeast |
5 | South |
6 | Southwest |
7 | West |
8 | Northwest |
7. If the Wind Speed is 30 mph or greater, consult the following table:
High Wind Effects Table
Wind Speed | On Land | At Sea | In Air | In Battle |
---|
30-44 mph | Travel slowed by 1/4, Torches blown out. | Sailing difficult, rowing impossible. | Eagle-sized and smaller creatures grounded. | Missiles at 1/2 range and -1 TH. |
45-59 mph | Travel slowed by 1/2, Small fires blown out. | Minor ship damage may occur (d4 HP), waves 3d6 ft. high. | Man-sized and smaller creatures grounded. | Missiles at 1/4 range and -3 TH. |
60-74 mph | Travel Slowed by 3/4, small trees uprooted, roofs blown off. | Ships endangered (d10 HP dmg) and blown off course, waves d10+20 ft. high. | No creatures flying except those from Elemental Plane of Air. | No missile fire, All non-magical weapons are -1 TH, Dex bonuses to AC cancelled. |
75+ mph | Travel impossible, only strong stone buildings undamaged. | Ships capsized, waves d20+20 ft. high or more. | No creatures flying except those from Elemental Plane of Air. | No missile fire, All non-magical weapons are -3 TH, 20% chance / attack that weapon torn from hand by wind, Dex bonuses to AC cancelled. |
Use of Magic Carpets or Brooms of Flying become very dangerous in winds over 35 mph. The percentage chance of a person or object being blown off is equal to the Wind Speed in mph minus the Carpet’s MV/10. This percentage is reduced by 5% for every 100 pounds of weight. It is increased 1% for every 5 lbs. below 100 pounds.
Use of a Potion of Gaseous Form in winds greater than 35 mph may cause dispersion of the gas so that the creature cannot reform.
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