Upvote:3
It really depends on what climate you are used to, but i think a sweater and a moderate jacket will be enough to keep you warm. (Don't forget the rest of the clothes) This link will direct you to the weather site of the swiss radio and television, which is independent and quite good in my opinion. Low will be at 8°C and high at 17°C.
When you want to travel to the mountains, bring warm clothes with you, as it probably will have snow in higher regions from this weekend on.
Upvote:3
I'm working next to Lake Geneva at the moment.
I'm going to work in the morning with a sweatshirt/jumper. No need for a coat. Though often an umbrella is necessary.
At lunch time it is sometimes warm enough that I'm just wearing a shirt.
Though as a disclaimer I'm from northern Europe. If you're coming from e.g. India your mileage may vary.
Contrary to stereotypes the shores of the lake actually have a pretty warm Mediterranean style climate, it's only once you get to higher altitudes that more stereotypical Swiss cold kicks in.