This tutorial shows how to install weather indicator for Ubuntu 11.10 Oneiric gnome-shell, original post is here

1.) First of all, install gnome-shell weather extension by adding ppa:webupd8team/gnome3

sudo add-apt-repository ppa:webupd8team/gnome3
sudo apt-get update
sudo apt-get install gnome-shell-extensions-weather

2.) Install dconf-tool by the command:

sudo apt-get install dconf-tools

then run:

dconf-editor

navigate to org -> gnome -> shell -> extensions -> weather. In right, change the value of woeid(See step 3 to get your woeid).

3.) go to weather.yahoo.com, enter you city and click Go. Put your cursor over RSS icon and you’ll see WOEID at buttom.

4.) Install gnome-tweak-tool

sudo apt-get install gnome-tweak-tool

Then launch it by searching Advanced settings. In Shell Extensions, enable Weather indicator extension.

5.) Finally, restart gnome-shell by Alt+F2 key combination and enter r.