Friday, May 30, 2014

From My Campaign - Detailed Weather Charts

  The originals were typed up on a selectric in '82, then photocopied, then re-typed in a Performa 405, then switched over, and now cleaned up on an Ubuntu netbook.

  I got the idea during a pickup game in 1982 where I was DMing for some friends. When we could get together I would run modules and such for them, all in Greyhawk. I had just read a Dragon article about weather in the campaign and decided to see how it worked. The adventure was ostensibly a scouting mission through the Vesve to spy on Iuz's border forts. Instead it turned into a survival scenario as an unseasonable blizzard swept the area.
  The players loved it, I loved it, and I decided to make a set of charts of my Seaward campaign.

  Hope you like them.

Note: The formatting is a little wonky because of Blogger, so please excuse the appearance.


Seaward Weather

First – Check for Unusual Temperatures: Use this chart to determine if a cold snap or heat wave is occurring:
01      Extreme Record Low
02      Severe Record Low
03-04 Record Low
05-96 Normal Temps
97-98 Record High
99      Severe Record high
00      Extreme Record High

  'Record High' or 'Record Low' means that the temperatures will be the maximum possible (i.e., if the base temp is 40, avg. high is d10 and avg. low is d20 a 'Record Low' means the high will be 41 and the low will be 20). A 'Severe Record' means use the maximums and add 1d6. An 'Extreme Record' means double the maximums.
  Unusual temperatures will last 1-6 days (roll d8-2 with a minimum of 1).

Second – Determine Base Weather: If there are unusual temperatures, follow those rules. Otherwise. roll on the following chart to determine the high and low temperatures, cloud cover, and base chance of precipitation;

Month
Base Temp
Avg. High
Avg Low
Clear
Part Cloudy
Cloudy
Precip Odds
Sunrise
Sunset
Newsun
40
d10
d20
01 – 23
24 – 50
51 – 00
46
07:11:00 AM
05:11:00 PM
Brightsun
42
d6+4
d10+4
01 – 25
26 – 50
51 – 00
40
06:45:00 AM
05:46:00 PM
Lambing
50
d8+4
d10+4
01 – 27
28 – 54
55 – 00
44
06:02:00 AM
06:19:00 PM
Blossoms
70
d10+6
d8+4
01 – 20
21 – 55
56 – 00
42
05:14:00 AM
06:49:00 PM
Plantings
72
d10+6
d10+6
01 – 20
21 – 53
54 – 00
42
04:35:00 AM
07:20:00 PM
Low Summer
78
d8+8
d6+6
01 – 20
21 – 60
61 – 00
36
04:22:00 AM
07:42:00 PM
Mid Summer
85
d6+8
d6+6
01 – 20
21 – 61
62 – 00
34
04:29:00 AM
07:40:00 PM
High Summer
83
d6+4
d6+6
01 – 22
23 – 62
63 – 00
33
04:35:00 AM
07:39:00 PM
Reaping
80
d4+6
d6+6
01 – 25
26 – 60
61 – 00
33
05:03:00 AM
07:02:00 PM
Casking
76
d8+6
d8+6
01 – 33
34 – 54
55 – 00
33
05:32:00 AM
06:20:00 PM
Frostflowers
65
d10+5
d10+5
01 – 35
36 – 60
61 – 00
36
06:02:00 AM
05:31:00 PM
Snowflowers
54
d10+6
d10+4
01 – 20
21 – 50
51 – 00
40
06:36:00 AM
04:55:00 PM
Darkmoon
40
d8+5
d20
01 – 25
26 – 50
51 – 00
43
07:09:00 AM
04:46:00 PM


        note: sunrise and sunset times are for mid month. Terrain and weather can affect when PCs see the sun, obviously.

Third (no precipitation) – Determine Wind Speed and Direction: Wind speed is determined by a roll of d20-2 (results of less than 0 are 0). For direction (this is where the wind is coming from) use the following charts:

East of the Stone Hills (1d6)
1
West
2-3
Northwest
4
North
5
Northeast
6
East



West of the Stone Hills (1d6)
1-2
West
3-4
Northwest
5
Southwest
6
North

On both charts add +1 from Frostflowers through Brightsun.

Third (precipitation) – Determine the Type of Precipitation: Consult the following chart to determine the type of precipitation. The precipiration will begin based upon the cloud cover: clear = late afternoon/evening; partly cloudy = around Noon; cloudy = early morning.

Dice Roll
Weather
Min. Temp
Max. Temp
Continue?
Rainbow?
01 – 02
Blizzard, Heavy

10
5

03 – 05
Blizzard

20
10

06 – 10
Snowstorm, heavy

25
20

11 – 20
Snowstorm, light

35
25
1
21 – 25
Sleet Storm

35
20

26 – 27
Hailstorm

65
10

28 – 30
Fog, heavy
20
60
25
1
31 – 38
Fog, light
30
70
30
3
39 – 40
Mist
30

15
10
41 – 45
Drizzle
25

20
5
46 – 60
Rainstorm, light
25

30
15
61 – 70
Rainstorm
25

45
20
71 – 84
Rainstorm, heavy
30

15
20
85 – 89
Thunderstorm, light
35

15
20
90 – 94
Thunderstorm
40

20
20
95 – 97
Thunderstorm, heavy
45

10
15
98 – 99
Tropical Storm/Hurricane*
55

5
5
100
Special







      • only East of the Stone Hills – elsewhere, treat as Gale 

  If the result of 'special' is rolled see the separate chart.

  Then see the following chart for specifics of the precipitation:

Weather
precip (inches)
 Duration
 wind spd
move
vision
Track
Lost +
Blizzard, Heavy
2d10 + 10
3d8 hrs
6d8 + 40
One-eighth
2'
No
50
Blizzard
2d8 + 8
3d10 hrs
3d8 + 36
One-fourth
10'
-40
35
Snowstorm, heavy
2d8 + 2
4d6 hrs
3d10
One-half
one half
-25
20
Snowstorm, light
d8
2d6 hrs
4d6
Three-fourths
Three-fourths
-10
10
Sleet Storm
1d2
d6 hrs
3d10
Three-fourths
Three-fourths
-10
5
Hailstorm*
1d3 – 2
d4 hrs
4d10
Three-fourths
normal
-10
10
Fog, heavy
damp
d12 hrs
d10 - 2
One-fourth
2'
-60
50
Fog, light
damp
2d4
d8 - 2
One-half
One-fourth
-30
30
Mist
dew
2d6 hrs
d10 - 1
normal
normal
-5

Drizzle
dew to 1
d10
d20-2
normal
normal
-1/turn (cum)

Rainstorm, light
d3
d12 hrs
d20
normal
normal
-10/T (cum)

Rainstorm
1d6
d12 hrs
2d12
normal
normal
-10/T (cum)
5
Rainstorm, heavy
d4 + 3
d12 hrs
2d12 + 10
Three-fourths
Three-fourths
-10/T (cum)
10
Thunderstorm, light
d6+1
d3 hrs
3d10
Three-fourths
Three-fourths
-10/T (cum)
10
Thunderstorm
d8
d4 hrs
4d10
Three-fourths
Three-fourths
-10/T (cum)
10
Thunderstorm, heavy
d8+3
d3 hrs
34d10+6
One-half
One-half
-10/T (cum)
15
Hurricane
d10/day
d4 days
7d10+70
One-fourth
One-fourth
No
30
Gale
d8/day
d3 days
6d8 + 40
One-fourth
One-fourth
No
20

Notes:
Hailstorms have a 20% of causing 1 h.p. damage per full turn of exposure to people with less
than A.C. 5 who do not have shelter. Rings, bracers, etc. do not count, magic armor does.
During Thunderstorms there is a 1% chance per turn of a lightning bolt striking the party. +10%
if the party is under a tree, on a hill in metal armor, etc. Damage is 6d6, save for half.
          For high winds see the Control Winds spell


Then modify the results with this terrain chart:
Terrain
Temp Mod
Wind Mod
Hills
none
plus or minus 5*
Light Forest
none
Minus 5
Heavy Forest
-5
Minus 10
Plains
none
Plus 5
Brambles or Briars
plus or minus 5**
Minus 5
Mountains
Minus 3 per 1,000'
Plus 5 per 1,000'
Sea Coast^
none
Plus 5
At Sea
none
Plus 10


**plus in Summer, minus in Winter
^within 20 miles of the ocean shoreline

Special Weather: If a Special event was rolled, consult this chartto determine the type of special weather event:


Hills
 Forest
 Plains
 Briars
 Mntns
 Coast/At Sea
Special Event
d6 
 d4
 d4
 d4
  d4
   d4
Wind Storm
1
  1
 1
 1
  1
   1
Quicksand

  2
 2



Dust Storm
2





Flash Flood
3


 2


Rock Avalanche
4


   
  2 

Tornado
5
  3
 3
 3

   2
Snow Avalanche




  3

Earthquake
6
  4
 4
 4
  4

Undersea Volcano





   3
Tsunami





    4


  and then this chart to see the effects of the special weather event;



Precip
Wind
Duration
Move
Vision
Track -
 lost
 damage and effects
Special Event








Wind Storm
n/a
8d10+20
d10 hrs
One-eighth
One-half
50
30
as Control Winds spell
Quicksand
n/a
n/a
n/a
no
n/a
n/a
n/a
save vs wands or stick and begin to sink*
Dust Storm
n/a
5d10
d8 hrs
One-eighth
1'
no
80
1 dam per hour if not sheltered
Flash Flood
n/a**
Nn/a
3d10 rnds
n/a
n/a
70
n/a
if in flood 2d20 dam, save vs wand for half
Rock Avalanche
2d10 min
n/a
d8 min
n/a
n/a
60
n/a
save vs. death or crushed; 2d20 dam
Tornado
1/hr
3d100+100
2d10 hrs
One-third
One-half
no
40
if directly hit as double strength Djinn
Snow Avalanche
5d10 min
n/a
d10 min
n/a
n/a
60
n/a
d10+4 dam, save or buried
Earthquake
n/a
n/a
1 rnd
n/a
n/a
50
n/a
as Earthquake spell
Undersea Volcano
n/a
n/a
d10 days
n/a
n/a
n/a
n/a
new island at end; 20% tsunami


Next (precipitation) – Determine if it Continues: At the end of precipitation's duration; if the result is less than the Duration chance consult this chart;

1    Down one step on precipitation chart
2-9 roll duration again and continue
10  up one step on the precipitation chart


   If precipitation continues, worsens, etc. the temperatures will change as needed to min/max levels.