Waxed cotton jacket for me too, if the weathers bad. If the weather is good, cotton shirt.
I try to keep the jacket for trips lasting only a day, and other occasions when you're either largely static or with transport, since it is a big old unit and doesn't exactly pack down much, but it still gets a good outing every so often.
Cotton shirts I have found to be surprisingly good for warm weather (yes the whole fortnight per year of it!), moreso than the synthetic T shirts I used to use. A lot cooler in the heat than the synthetics, but because the cut is looser and doesn't hug the body it still doesn't take forever to dry like a cotton T shirt would.
I should like to get one of those gabardine/ventile type smock jobbies as a sort of extra in between option, and I reckon it would also do well in extreme cold dry conditions with the right layers beneath it, since all the water will be quite reliably frozen under about -7 degrees or so, but they are quite pricey and getting one to look non-military enough could be a challenge.