Your question is very poorly constructed but I will try to give you some steps suggestion:
1) Organize your data into a csv file containing XYZ where X and Y are the coordinates of each weather station and Z is the variable you want to interpolate, e.g. rainfall.
2) Import it to qgis -> Check this online tutorial: http://qgis.spatialthoughts.com/2012/01/importing-spreadsheets-or-csv-files-to.html
3) Go to the Plugins menu, then Interpolation > Interpolation. If you don't see this option enable at the Plugin Manage.
4) Select as input the layer of point representing the stations
5) Select one interpolation method e.g. Inverse Distance Weighting (IDW)
6) Try different parameters to ensure a good interpolation.
If you need more specific explanation try to give us more details!