Someone was asking about light packable jackets for Switzerland in that forum, and I posted this. I thought it would be useful here, where more people would see it. These are great prices for Patagonia quality. I am not putting it in block quotes because I wrote it.
I take a lightweight, non-bulky down jacket on every trip to Switzerland, regardless of the month. Folded and pressed flat in a ziploc bag, it compresses to a package 1/2 inch thick until I need it.
If you don’t have such a jacket already, Patagonia has some good ones on sale for $139, in a variety of colors and sizes. Men’s:
https://www.patagonia.com/product/mens-down-sweater-jacket/84675.html?dwvar_84675_color=CRMD
This one is a pullover, not down, but should also pack small:
And if you wear S or XL, this hoody is only $89:
Womens’ option, not down, in lots of colors and sizes for $99:
This is the one I have, only available in small sizes at the sale price of $119:
The women’s down sweater for $138 would be a bit warmer, but again is only available in small sizes:
https://www.patagonia.com/product/womens-down-sweater-jacket/84684.html?dwvar_84684_color=BURD