xfce4 weather plugin without internet connection
 

i would like to have xfce4 weather plugin that saves its data locally without internet connection even updating data twice a day.

I'm not sure I understand you. Are you wanting to use the plugin without accessing the internet? That's were it gets its data!

When the weather plugin stopped working recently (it's working again, at least for now) it was pointed out that the source of the weather information is hard coded into the program itself. This means that if you wished to use a local file, or another source, for weather information you would have to change the relevant code and compile it yourself.
This thread gives some information on how you could either change the source of information or use another plugin to do something similar:
http://ubuntuforums.org/showthread.php?t=1875487

the weather plugin needs to be constantly connected to internet. but i would have weather forecast and data even if i turn off the computer and then reboot without connecting to internet. thx

On startup, and at intervals, the weather plugin connects to the internet for an update and if an update is not found it will not display the weather. If you want to change that you will have to recompile the program as there are no options to change this.
Alternatively, you could script something to work with generic monitor plugin.