Help to make a Blight condition

I do not really understand what you are asking.

The Wiki is your friend; use it. This is for all things weather-related:
http://cs.elderscrolls.com/index.php/Category:Weather_Functions

If you are trying to determine whether the weather is currently Blight:
IF GetCurrentWeatherID == 01F8B26B
-OR-
IF GetIsCurrentWeather AshstormBlight == 1

If you are trying to create a Blight Storm:
SetWeather AshstormBlight 1
-OR-
ForceWeather AshstormBlight 1

The "1" at the ened of these two is optional, and tells the game wether or not you want it to just normally change the weather when it wants to, or wether you want it to hold the current condition until something else overrides it (like fast travel, etc.).

Edit:
And, as Qwerty pointed out above, there are two separate Weather ID, "Ashstorm" and "AshstormBlight."

Also, from these examples, you can see that Oblivion is not always consistent. Sometimes it wants FormID's; sometimes it wants EditorID's, and sometimes it wants ReferenceID's. It is sometimes even less clear about which type of ID it is looking for, so, let trial and error be your guide here.

Also, keep in mind that there are Blightstorms (which only occur within Ghosfence) and regular Ashstorms (everywhere else)

Me n sorrow are already making blight conditions, so dont worry aout that, we already have most of the weather done

I just asked how I will set this as condition to my packages.

I will try whatever you told me, and then I will create an Ashstorm to see if they hide in houses.

I will try this later.

That worked! Thanks