Hi Raymo,
The sensor temp, along with a heap of other data is recorded/embeded in the image. If you right click on 1 of your images, select "properties". This will open a window, click on details and should be able to find it in there. You can also use firefox with the Exif Veiwer addon to view it as well.
Hope this helps
Cheers
PS here's a link with some info on Exif files
http://photographylife.com/what-is-exif-data