To put it on Strings.xml
you have to add this :
<string name="Temperature">Temperature: </string>
Then if you want to use it from Strings.xml
you do this as follows :
List.add(getString(R.string.Temperature) + matrice[1][2] + " ºC");
To translate it you'll have to create different values directories for the language with the suffix of the language code.
See the documents
EDIT(parameters String)
Adding the parameters as @trooper said, would be like this :
Your Strings.xml
should be
<string name="Temperature">Temperature: %1$s ºC</string>
Then in your java code you have to use this :
List.add(String.format(getString(R.string.Temperature), matrice[1][2]));