You need to pass in unicode text:
u'technologieën in °C'
Do make sure you use the # -*- coding: utf-8 -*-
comment at the top, and make sure your text editor is actually using that codec. If your editor saves the file as Latin-1 encoded text, use that codec in the header, etc. The comment communicates to Python how to interpret your source file, especially when it comes to parsing string literals.
Alternatively, use escape codes for anything non-ASCII in your Unicode literals:
u'technologie\u00ebn in \u00b0C'
and avoid the issue of what codec to use in the first place.
I urge you to read:
before you continue.
Most fonts will support the °
, but if you see a box displayed instead, then you have a font issue and need to switch to a font that supports the characters you are trying to display. For example, if Ariel supports your required characters, then use:
matplotlib.rc('font', family='Arial')
before plotting.