For me, if I were hiking in your kinda weather ( and I have - almost - spent some time hiking in Tasmania) I'd probably be layering a little more than looking for just one jacket. Also lets me pick and choose and dry layers out easier.

Now of course to me the amusing part (and it was to me in Tasmania as well) was people referring to 9 to 15 C and rainy as "cold" (you keep using that word..) Although to be fair hiking for 3 clicks through a horizontal downpour on the bottom of South Coast trek was a bit less than what I'd call "warm". I did actually get "cold" on top of the ironbound range in about an 60 - 80 km/h wind with rain 1000 meters up.
but I was warm once I put on a merino and the jacket.

What I carry in your summer was two nice merino long sleeve shirts, a 100 wt fleece and a lightweight waterproof breathable jacket/windshirt. In more like your winter conditions I would add my MEC northern lite primaloft pullover - this is a very light synthetic jacket with primaloft insulation.

Unfortunately MEC doesn't make them anymore. (well they make something of the same name but it is now heavy and sucks because they changed it) But there are other alternatives out there.

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