Randomized Weather on Loaded Saves

[merc4ulfate]

A simple question. What governs the weather?

You can save the game in a career then reload the same spot and have different weather. Why?

I decided to give a particular encounter another try and loaded the point just prior to the encounter. I noticed instead of a monsoon I had clear skies. I reloaded it again and saw a monsoon again. I got the monsoon 3 out of 5 reloads but I do not know what governs this and why the randomness of the weather on loaded saves.

I'm not really worried about it I just wanted this answered for self knowledge.

Generic Mod Enabler - v2.6.0.157

1_TriggerMaru_Overhaul_2-5
1_TMO_25_small_patch
RSRDC_TMO_V502
RSRDC_V5xx_Patch1
Improved Ship Physics 2.6_TMO_RSRDC
TMO_Visuals_for_RSRDC
FJB_Navigation_Maps
FJB Color Navigation Map
Gyoraitei
11 New Ships + Yamato AA Fix by Miner1436
Ship pack 1
SMALLER SEA PLANTS SMALL
SMALLER SEABED ROCKS
#5 Depthcharge Sound
#2 Other Clouds
Webster's Eliminate Floating Plankton for v1.4 and v1.5
Aircraft_reflections
Hull_Numbers
TMO Smoke Mod
Classe_Balao_CamoTri
MAP_TABLE_MOD_1,3
TMO+RSRDC missions pack