I know there have been other discussions about this topic but I will land on a Sunday in July approx 10:30 and want to be sure
there will be trains to get me to Colmar , I was not sure if Sunday had less options for train frequency , it looks ok on the Swiss train site but I know very little so that is why I am asking .
It will be OK by train. Sundays have slightly less trains, however the difference is not great.
The SBB website ( https://www.sbb.ch/en/ ) can be taken as the definitive source of train times.
I just checked times for Sunday 7th July, starting at 11:00 and got the following:
Zürich Flughafen dep 11:36, Colmar arr 14:05
Zürich Flughafen dep 13:18, Colmar arr 16:01
Zürich Flughafen dep 14:38, Colmar arr 17:05
Zürich Flughafen dep 15:18, Colmar arr 17:28
Zürich Flughafen dep 15:38, Colmar arr 18:05
Zürich Flughafen dep 16:18, Colmar arr 18:35
Zürich Flughafen dep 16:38, Colmar arr 19:05
Plenty of choice!
Note, in Basel, due to building work the annex where the trains to Colmar start from requires you to exit the main station and walk along the street for about 200 metres. It is signposted.
!Did this exact trip last year, and took Chris's advice - he was spot on! It was a breeze.