Switzerland- best time to visit?

[JanuaryBones]

At the planning stages of a holiday next year. I have family in Switzerland, near Basel, who I would like to visit. I just wondered when the best time to visit (weather wise) would be? Last time we went in September and it was glorious but not sure if that's the norm.
Anyone with any experience of the best time of year to visit? I can't ask my family as it's a surprise visit!
Also, any locals know what the Covid situation over there is in terms of getting a test (if necessary) and what the vaccine take up is like?

Bump

Any time is a good time for Switzerland in my book.

I went in August and it was great! We went by train so couldn’t say what the roads are like (busy or not).

Depends if you want sun and heat or wintry weather.

We’re aiming to go mid-August next year. It’s lovely then (and the glacier in Saas-Fee will be open for skiing).

I were fully vaccinated (COVID-19). May I know that Do I need to get negative COVID-19 PCR test when go to Switzerland fromUK?

@JanuaryBones

Late May for all the flowers