I have invested in these two items. Kifaru woobie xpress and Snugpak poncho.
I believe they will make me comfortable whatever mother nature throws my way.
Together they form a "minitent" in which one can sit down
with feet tucked under the rainponcho and woobie having ample isolation against cold.

Even warmer when arms are pulled inside.

Snugpak poncho pack size is a couple of (manly)fists. Kifaru woobie bigger but can be compressed quite a bit. Perhaps into a size of 3 litres.