Random events are a set of events which can occur many times. Most random events affect all countries, although there are a few random religious events which affect only limited sets of countries (i.e. the events which allow American pagan countries to convert to Christianity) and a very few which are targeted just to one country.
Technically, any event which has the attribute "random = yes" is a random event. In vanilla 1.09, random events are defined in two files: randomevents.txt and randomreligiousevents.txt.
Every country will get one random event roughly every 14 months, although the time between events can range from 12 to 24 months randomly. Note that if an event's triggers match your country, but it has no effect, then you will see no effect. (For example, this can happen with the events Heretics and Conversion of Heretics, if you have no wrong-religion provinces.) Random events may strike on any day of a month. I'm not sure of any of these numbers; more testing needs to be done here.
The random event timer is reset when you reload the game. That is, you'll have to wait at least 12 months from a reload to get any random event.
Random Events Listing
A listing of random event triggers and effects for 1.08 can be found at in the EU2 FAQ section of the forums: Random Events FAQ 1.08. It would be nice to transcribe that information for 1.09 here.
For 1.09, we only have a few random events listed here. You can help.
About the Listing Tables
All the events are grouped by 'family', following lawkeepers groupings. Every event will be displayed with the event id number, name, conditions, general effects, and specific numbers for scaled effects.
Conditions for an event based on domestic policy sliders, techs, other variable are shown with the variable name, a number and optionally a plus or minus sign. '-' means this number or lower, and '+' means this number or higher. If no plus or minus is shown, '+' is assumed; i.e., "infra 7" means infrastructure tech 7, 8, 9, or 10.
Most random events are scaled on the basis of the size (in city provinces) of the country. Larger countries tend to get bigger effects. Those events are listed with an 'x' in the place of the second number, like 9x005. In these cases the effect of the event which is common to all 6 country sizes is listed in effect, for example, "+N cash" which means you gain cash in the treasury. The exact amount you gain is listed in the six remaining positions of the table. The precise event number used for scaled events is standardized: the 'x' is actually one of the digits 4 through 9, as shown in the table to the right.
Inflation and Cash
These events give or take cash or inflation.
|94018||Exceptional Year||+100d, -2 inflation|
|94019||Exceptional Year||1400-1549||+100d, -2 inflation|
|94020||Exceptional Year||1550-1649||+200d, -2 inflation|
|94021||Exceptional Year||1650-1799||+300d, -2 inflation|
|9x060||Corruption||-N cash, stabhit OR inflation +1||-25d, -2||-75d, -1||-100d, -1||-150d, -1||-500d, -1||-1000d, -1|
|9x061||Corruption||-N cash, stabhit OR inflation +1||-25d, -2||-75d, -1||-100d, -1||-150d, -1||-500d, -1||-1000d, -1|
|9x071||Bank||1650-, infra 7||-5 inflation, +N cash||75d||150d||200d||300d||500d||1000d|
|9x072||Stock Exchange||1750-, infra 7, trade 9||-2 inflation, +N cash, +M infra||25d, 250||75d, 500||100d, 750||250d, 1000||500d, 2000||1000d, 5000|