In addition to the aforementioned:
Consider adding a 30gal trash bag (I call it a "life saver")...it weighs nearly nothing and has many uses, the most important is that it's a vapor barrier and will retain warmth at your core.
First, cut a hole for your head in the top and at the arms. Try it on. Should not be too snug or irritate at the neck, arm pits and shoulder. If it
s too snug...get a larger size.
Second, when and where should you wear it?
Secondly, I've found that if the outside temp is 40 degrees F/4.4 degrees C...walking I will generate sufficient heat to be very comfortable until the sun works it's magic...then I take it off.
Thirdly, a poncho, as JW mentioned can come in handy...then again, sometimes it's a light rain or mist, you may not want to take out the poncho. In this case, put the "life saver" over your fleece. Now the fleece can be as light weight as a vest, rather than a full jacket. Remember, it's your core your looking to protect...then arms are just extra.
Lastly, since you probably have trash bags at home already...it works for you frugal approach to gear.
Before you depart, give the "life saver" a try. Experiment when and where you can use it too best effect.
Buen Camino
Arn