setOvercast 1 and simulSetHumidity 0, can cause thunderstorm with lightning on a clear sky.
You can also setOvercast 0 to have a cloudless sky, but use SetHumidity to bring the clouds back
Warning
This command is listed as broken on the wiki.
Description
Sets simul cloud cover. This command does not affect overcast value.
This command was not implemented up until Arma 3 v2.18
Syntax
simulSetHumidity humidity
Parameters:
humidity: Number - 0 (min): clear sky, 1 (max): heavy cloud cover
Returns: Nothing
Examples
Example 1
simulSetHumidity 1;
Example 2
When combined with setOvercast 1 this command will also start random strength rain.
skipTime -24;
86400 setOvercast 1;
skipTime 24;
simulSetHumidity 1;
Creates rainy looking weather, followed by thunder in about 10 seconds and rain in about 20.