This works in local tests (care with the spelling of weather not wheather):
1. Templater > User function name
getWeather
2. Templater > User function command
curl wttr.in/Berlin\?format="%l:+%c+%t+feels+like+%f\nSunrise:+%S\nSunset:++%s\nMoon:++++%m\n"
3. In the template itself
<% tp.user.getWeather() %>
4. Results in
Weather: Berlin: 
-5°C feels like -6°C
Sunrise: 06:53:58
Sunset: 17:44:25
Moon: 
Not exactly what you want but hopefully helps with troubleshooting.